[namnibor]

I have both the Virus KB and KC and the aftertouch is remarkably responsive. Now I know this does not answer your question but what I would do is route a modulation path to aftertouch as the destination and make that modulational item be something of a profound initial attack for example a filter with envelope set to zero attack and max level and then test that to see if it may simply be that whatever LEVELS of the modulation routings are on a patch you have been having trouble getting response on are simply levels set too low for some reason. Whomever had your Redback previously may NOT have liked aftertouch and thus, set levels of aftertouch GLOBALLY to either off or incredibly low. THEN you may look into if the same make of FATAR keyboard was utilized in the Virus KB or KC, as I read somewhere a few times over that a different FATAR keyboard type was used but with aftertouch all the same. Read in manual or the online pdf ALL about aftertouch and also GLOBAL parameters and if you still come to having no or little responsiveness via aftertouch, then contact Access Support to see if there's just something that's an oversight in the settings or if any known problems exist AND you may want to make sure you have the most current O.S. loaded as for all you know, there may have been a bug that was fixed in same order of you question.
I can say the aftertouch on both my KB and KC are phenomenal and very useful for making a sound further evolve. You should not have to press so hard that a key pops off. it may behove you to ask the seller whom you purchased her from if this was an issue as it is number one reason I would never buy an instrument at a pawn shop nor even from Craigslist, as both localities reflect the "underbelly" of society, trust, and integrity.
Good luck in your quest!
Robert