I'm a controller player. Swapping sets is a piece of cake, but remembering what set you're on after dodging AoEs and mechanics isn't as easy as keyboard/mouse people. Sometimes we need four sets just to keep everything organized.

It'd be awesome if each hotbar/crossbar had a faint "glow" to them with preselect colors. So if I'm a DRK and I need to stop DPSing and start tanking, I can quickly glance down to see a "red glow" color around my buttons knowing I'm on my DPS#2 AOE bar, so I can swap to to my "blue glow" color and focus more on what's happening in the battle.