Think I found the sweet-spot for my cards. The R9 280X ASUS DC2T's are amazing! These results are from 24-48 hours of mining.
W7 64
4GB RAM
3x 280X ASUS DC2T @ 1160/1600 and 1x 280X Gigabyte Windforce 3X @ 1100/1500 with the flags -t 0,0,1,1,2,2,3,3 -a 2. Total = 14374 CPM. (Avg is ~3593 CPM.)
Temps are ranging from 62C to 72C at 60% fan-speed with ambient at 25C-30C depending on the time of day. If running 4 instances, one for each card, each card would hit 3300-3400 CPM (why?).
My single 280X Sapphire Dual-X @ 1100/1500 hits 3362 CPM. It has low ASIC rating and fans that apparently are prone to fail; I'm just gonna leave this as is.