bx_digital is a great overall tool for mastering (offers a lot of special features combined), which I will use it for, but in my honest opinion not the best M/S EQ or EQ in general for mastering and I want to tell you why:
The interface is a bit clumsy and hard to read. Sections aren't clearly separated, parameter which obviously belong together aren't layed out as close as they should be and some parameters are placed on quite unusual places or their use is not easy to understand due to an confusing parameter name. - Now this is a problem I encountered in many brainworx plugins, and although I know the guys of brainworx work hard and do great things to their plugins under the hood, this a thing which turns me away from using their plugins, everytime I feel to dig into it/them again. -.
No Mute/Bypass for MID or SIDE processing. - Now bx_digital offers plenty of options to solo a single band and the section (Mid or Side) connected to it. But it doesn't offer a way to bypass or mute the EQ processing of a section, which is in my opinion quite a vital feature to an M/S EQ (especially for a high-end MS/ EQ of that kind) and I really was suprised that bx_digital didn't has it.
Why would you need that, you ask? Well, You want to bypass just the mide or sides to adjust the EQ bands and control whether the processed signal really sounds better than before (look how the EQ altered the signal of that section only).
In this plugin, you need to disable all other filters of a section to achieve that. A No-go for me. -.
No fixed solo for bands. - The only way in bx_digital to solo a specific band is to tweak (actually change its setting) and hold a band-related parameter or disable all other filters. It is not possible to solo more than 1 band and not possible to solo a single band in a fixed manner. Bad. -.
Auto-Solo and/or Auto-Listen itself is a mess - Auto-Solo soloes the section (mid or side), Auto-Listen actually the frequency band, but Auto-Listen only soloes while you tweak, if you rest the parameter, it stops soloing.
Beside this you can choose between whether you want to solo the gain, frequency and bandwidth of the soloed band. Why should anyone need that?
If I want to solo a band, I want to hear how I change it, not anything else. Here I think Dirk went too much into the detail in a rather unneeded feature and wasted time and capacity in place of more important aspects of the plugin.
Conclusion: The logic and sense behind the concept of these both functions I feel as very unuseful. -
The slopes of High and Low Shelves are fixed, not adjustable. - When not providing a Q-value (which is common), you should provide at least different types of slopes. But here nothing.
Tip: You can use reduce the presence or bass shift to alter the slope a little but as described in a minute this also affects adjacent frequencies. -.
Parameter values do not reset to its default value at double or right click. - It is only possible by using CTRL or CMD and click. - You might say this is nitpicky, but if you use the plugin more often you definitely have a problem with that. -.
Presence and bass shift features affect other bands. - I think the idea behind that is great and unique to bx_digital but however it isn't as useful for me when bass or high-end boost reduces the frequencies ranges around. Yes, a Pultec is based on doing exactly that, but this one is not a Pultec-EQ, it is a transparent mastering EQ, which you use for sublte changes, not to deconstruct the EQ-curve of your entired mix.
Speaking about the controls of Presence and bass shift in the dedicated sections, the layout is actually assymetrical between the Mid and the Side sections. On the left side, the dynamic EQ is at third place, while at the right side the dynamic EQ knob is at first, shifting both controls. This can be a little inconvenient if you're adjusting them both, but that just a simple note. -.
Dynamic EQ does not offer threshold and adjustable times. - This a new feature of V3 and a succesor to the in-built De-Esser and you can adjust the frequency but to use it as clear dynamic EQ it is limited in what it can do (no threshold, no accurate Attack and release times). -.
The visualized graph does not give a clue about which filter is doing what exactly. - There is no visual help to detect immediately which filter does what in the signal. You need to tweak the filter to get an impression what is doing what.
Especially on long sessions with many filters engaged a bad thing, where you don't recognize the setting in an instant. Just a little mark with the name or number of the filter could help, but isn't there. -.
No quick reset for Mid or Side section. - If you completely think with the eqing of the side and want to readjust the parameters for the mid (or vice versa), there's no way to reset all parameters for a section only at once.
bx_digital might have been a great tool for years and a pioneer as M/S equalizer once, but there are really better options available today, just for the EQ part.
Other feature wishes:
Gain Scale - independent for Mid and Side.
Disable the graph with the discontinued lines of the unused filters in the analyzer (Quite distracting).