I have two meanings for the binary comment:

1. You're either at 0 or full right now if you're getting healed with WoG. Yes, this will change with Cata but then number 2 is a bigger problem.

2. Swapping to heal people who are either both getting focused or if your whole team is getting AE'd is *hard* with WoG. It's not impossible, it's just hard.

I'm sure people will be successful with the Rets--I just think it's going to take more work and will have an ultimately lower cap on your max performance.