I'll keep this one short because the main points have already been mentioned by my fellow KVR reviewers below.
In short: yes, this does sound like a Roland synth - actually, it's the very first to do so in the virtual world besides Roland's very own products. No, I haven't used a JX synth in the past but a couple of other analogue Roland synths and the PG-8X shares the same rubbery, lush and fat character inherent to Roland synths. Similar to TAL's synths, this one is worth it for the chorus alone.
I acknowledge that presets are crucial for many, so the PG-8X being sysex patch compatible with the real thing opens up a whole new world of possibilities. Aside from the original factory banks that Martin supplies, you can find hundreds of patches on the internet. As I am more of a roll-your-own guy when it comes to synth sounds, I found the surface nicely laid out and inviting for tweakers. Making a vibrant pad is a matter of seconds, making massive bass patches is so, too. And the thing is: it instantly sounds like Roland. Right there in your DAW. For free. That's simply amazing - especially if it doesn't set you back 150€ if you purchase from other devs with a similar claim.
I'm a Mac-Head as well (AU only at that) so I'm using an older beta with all its quirks. But since I could not believe that you'd get such a quality plugin for free, I donated to Martin in order to support further development. I suggest you do the same if you're after a Mac AU version as well. On top of that, Martin is a very responsive developer (just read the dedicated forums) and seems to be a very nice guy - so there are even more reasons to support indie devs like him rather than the big corps. If he comes up with a virtual MKS-70 or models another Roland synth of yesteryear, I'll be the first in line to buy it without a prior demo run.
This reviewer is old enough to say, I've been around. I've owned three JX-series synths, and am intimate with the character of the sounds & quirks of each.
When I discovered the PG-8X here on KVR as a passing post, I got excited. Then a little crestfallen when it was stated to be a PC-only VST, and I'm a Machead. However, with a little tenacity, you CAN make it work on a Mac, using VFX V-Machine software (up to OS X 10.7.x), which is a blessing. Using this configuration and some tricky headphone out --> audio interface in --> Ableton Live/Logic Pro audio path, it's relatively painless. As of this writing, the author (Martin) is working on a Mac VST.
On to the quality -- yes, I did give it a 10 out of 10. The interface is not too clunky; in fact it is modeled after the Roland's very own PG-800 proprietary hardware programmer, which was intended for the JX series of synths. With this interface and my patch sheets, I was able to dial up a few of my own custom patches with 100% accuracy; the sounds were an exact replica of the JX8P! And for those who care: yes, I do have patch sheets of my patches from the 80s and 90s, thanks to pre-internet studio record keeping.
Sound quality is outstanding and beautiful. Very little latency. It is so convincing as a JX emulation, I find myself hitting the keys kind of hard to trigger some of the nuances that are buried in certain JX patches. If you have ever owned a JX8P, JX-10, or MKS-70, you understanding exactly what I'm talking about here about the tactile response. Point is, there is absolutely no doubt whatsoever about the PG-8X's ability to emulate the JX8P. It is an accurate emulation.
Initially I had a problem with some of my patches clipping; but after some research & memory recall in my own brain, it was not the fault of the PG-8X, but rather from a setting I had on my own personal JX8P "back in the day." The hardware JX-8P had an impedance switch of the back of the unit labeled "Level" with three settings: L-M-H (Low, Medium, High) for the stereo 1/4" outputs. Chances are I had mine set to Low or Medium. So naturally when I entered my program patch and it occasionally clipped, the simple fix was to turn down the VCA Amp level to a more comfortable non-clipping level. If you get clipping, any at all, it's due a combination of what the original programmer (like me) and their JX8P's level switch set too low when designing the sound in the first place.
To stress and prove this point: If you have any clipping at all with a patch? Turn down the VCA AMP LEVEL, known as the JX8P menu item 61. Example: download my patch titled "RUMBLEFISH" here (http://home.earthlink.net/~finnkit/), and program it into the PG-8X. You'll find it occasionally clips. Currently the setting I have in Rumblefish patch for the VCA Amp Level is 99 (out of 99). Turn it down to around 70; and miracle of miracles, no more clipping! This clipping issue is not any fault of the plugin. It is due to huge number of legacy patches that contain overdriven VCA levels. So no points against the plugin here. This is what us pre-VST folks had to deal with in the real world back in pre-DAW history, using hardware synths.
Supposedly the plugin has the ability to load legacy patch and or bank dumps from sysex MIDI files, which is a blessing! Unfortunately I cannot test it at this time to verify this (see above: I'm a Machead).
Martin was even thoughtful to include an extra noise generator to simulate the notoriously noisy chorus that is built into the Roland JX and Juno series. This was also sold separately as Boss CE-300 rack unit chorus around the same period in time. Martin plans to release a separate chorus plugin using this code. And yes, just hearing that noise (which has a level control and off setting) does trigger some nostalgia. But thank goodness you can switch it off, and keep that digital purity in your DAW.
There is the ability to switch patches from the GUI, which is a benefit especially if you are using Ableton Live. This feature is unstable using smaudiopro.com's VFX Mac app, however that is the fault of VFX, not this plugin. Of course this will probably be a non-issue once there is a Mac version of the VST. A better, more intuitive (and visually representative of the JX8P's display) patch selection seems to be coming in a future update, as hinted by teaser pictures of a modified GUI on the ML-VST Facebook page.
The quality setting in the hidden panel is fantastic - I do hear a discernible difference as I go up in quality without much hit on the CPU. I also love the voice usage counter, especially when you can tell when a voice has been released.
There are just a few things I wish the plugin did have:
a Mac VST (which is promised and in the works -- as of July 2012);
a host-syncable or MIDI-Clock synced LFO, something the original hardware JX did not have;
and finally the ability to make the plugin able to produce more than the 6-voice limit that the hardware had, and make it user variable? Say, 24 or 32 voices would be nice.
Those wishes aside, Martin has managed to create a truly accurate emulation of the JX8P. The proof is in the pudding by personally comparing my custom patches & old recordings from the 80s and 90s of my old JX8P versus the same sounds programmed in the PG-8X; if that's not enough, then listen to the venerable SOUNDTRACK patch, which simultaneously shakes the windows and shimmers like water; he nailed it! Thanks, Martin!
If you haven't done so already, open up your virtual wallets and pocketbooks and donate to the development of this plugin, you one you didn't know you needed until today. And do so quickly before some larger VST company purchases the rights for this emulation from Martin (and proceed to royally screw it up... cough cough Arturia cough cough).
Martin also has a Facebook page dedicated to the updates: http://www.facebook.com/MLVST