(with the caveat to move to suggestions if this would be preferred. however, the systems not live, and you're looking at it's uses now, so
With the new doublestrike mechanic going into effect shortly, may I suggest you turn your attention to using the same system for mobs, with the caveat of lowered to-hit by them per-strike? This would allow for lower strength mobs, making weakening weapons more powerful, satisfy to a degree those folks with middle-ground ac, as well as give a boost to DR builds a bit?
mathwise, taking something along the lines of (for simplicity)
6x50 damage (lialat (sp) being an already familiar example)
dr effect using all those 5/magic items we're all swimming in at this point:
6x45
saves 30 HP
60 to-hit
-5 progressively
60/55/50/45/40/35
saves anywhere from 50-250 hp depending on build
It really does seem like you've opened up yourself some breathing room for design space there if used properly, and might go quite a ways towards dealing with quite a few longstanding complaints.
/just my 0.2 insanity for the day, I suppose.