So right now bonuses are capped at 6 points, at "Maximum!". It's possible to exceed 6 points on a given bonus through various combinations of trinkets, UVs, armor and shield bonuses, but all you get is "Maximum!".
So what if, instead of a rather useless low damage bonus on each Chaos set piece, they instead gave a bonus cap increase? So with one piece you'd be able to get up to 7 points of bonus, and with two pieces you could get up to 8 points. Call them "Ludicrous" and "Plaid", I dunno.
With a few UVs, a swiftstrike and some trinkets you could have a DA with a "Ludicrous" ASI and a "Plaid" damage bonus vs Undead...
While I'm all for making Chaos more viable for common use, I am afraid to say you are taking the wrong approach here.
You will need another approach if you wish to make Chaos viable for common use. Even if you could exceed caps with the set, it would still be neglected I'm quite sure. I, for one, would almost stop using it altogether if they altered its current universal damage bonus for that.