Again, while finding low cost good sounding solution to my mixing problems, I found that huge amount of people recomends (sorry for comparison again, but I think this one is needed) SPL transient designer. I dont know how you guys, but 200 bucks is huge amount of money for me and I'm always feeling wierd about plugs with two buttons and such a gigantic price tag. So I went comparing.
I took little saw note with no dynamics at all and tried to watch on osciloscope whats happening when processed by Bitter Sweet and demo of SPL. I was interested mainly in steepness of reaction and overall shape of attack effect. I found that both used curved shape of attack, not just linear ramp. Good. I didn't meature precisely by any means, but as far as the attack steepnes went, they both didn't "click" right to highest volumes. They "climbed" there. At the first SPL seemed about 0,3ms quicker, but after some repeating both designers ended up in "1-2 ms" range.
Now if you look closer, right under Bitter Sweet big button is time adjustment slider. By listen I wasn't sure what it affected and yeah, it was length of the decline. This is feature SPL doesn't have. On the other halnd SPL has a sustain phase adjustment that kind of raise level back again. This is something Bitter Sweet could use in next version, yes. :)
Any other differences? Well if you send more notes in (= signal that just "bubbles" volumewise), they behave pretty much the same. Wait until it drops down doing nothing and then waiting for another attack. Both can do ridiculous spike heights, but in that area, SPL can do a bit more ridiculous ones. But I think nobody will use this feature anyhow.
Only serious character difference I found was by getting them overdriven. (= attack clipping) SPL shows that it really has some analog code inside and it slowly saturate the signal in kind of pleasant way. Bitter Sweet limits it self by some soft limiting if at all and tries to remain original character of the sound, which could be good thing too. When you have already saturated material, you don't want another coloration.
So, it can stand up to it's 200$% more expansive oponent. It miss sustain feature, but attack phase is adjustable by even more flexible way with similar results soundwise, sometimes even cleaner.
Now I know what you're thinking. Try Dominion, it can do it all. You know..., as far as I love Digital Fisphones, Dominion didn't do as well. It is much more featured than these two, but attack is slower, decline not so elegant and main problem is that it saturates really quickly and not so pleasantly. It brings up even some DC offset into the signal. So Bitter Sweet is actually better choice to mimic the SPL attack behaviour.
For all "I need some transients and don't have bloody 200 bucks!" guys like me definitely a musthave! :)