Just recently did Less-Rabi, found an incredibly easy way to down him.
A Moonkin's Solar Beam (10 Second Silence, 15 glyphed). We had a disc priest (Smite spam healing), Moonkin, Shadowpriest, Fury Warrior, Frost Death Knight.
We downed the boss to ~75% or so, then popped the silence and nuked the boss with 5 dps, no hero.
So the "exploit" is that the boss shouldn't be silence-able, but is affected by solar beam. As long as you have enough DPS for a 20second 300k health nuke, you're fine.
EDIT:
If its a repost, please delete. I searched "4.0.1 Less-Rabi" "Easy Less-Rabi" "Less-Rabi" and "Solar Beam", got nothing.