I implemented a simplified version of the ISBoxer step keys this weekend, and it's quite lovely. Here's how I have it set up:

Hotbar 1:
1: Main attack sequence macro for SINGLE TARGET
2: Proc macro for SINGLE TARGET
3: Main attack sequence macro for AOE
4: Proc macro for AOE (usually the same as single target)

I set my 1 key to have 2 steps - first sends 1 to all, 2nd sends 2 to all; my 3 key does the same - sends 3 and then 4 to all. I'm happy to say it all seems to be working well; no real DPS increase, but it is more convenient than what I had been doing, which is a huge plus.