From the department of changes that were on my list four months ago before I got busy and distracted:

You are somewhat less likely to miss an attack because of sensory distortion (symphonic echoes, etc.) if you're being ganged on. I would prefer this to instead be a chance to hit one of the other people ganging on you instead when you miss because of echoes, but I wasn't ambitious enough in my current state of shaking the CF-coding rust off to attempt that. Possibly I'll retrofit to that without warning at a later date.

This is also true, although less so, for evade. That is to say, if you're crowding around someone and ganging on them, evade will do a bit less for you.

At this point, this amounts to all of the changes I've had in mind to make either skill, and it probably will have little to no effect in 90%+ of the fights in which they factor.