It seems everyone swears by Frenzy + Sidearm. I find that it is incredibly slow at killing a group, the bigger the group the slower it is to use Frenzy instead of Cleave. Even with 2 targets there is a question as to whether Frenzy is faster. Not to mention the extra targets seem to outweigh the penalty for life restore on AoE attacks so you're missing out on some serious life leech with 3 or more targets for sure.
Granted I am only in Act I inferno, but my gear is pretty crappy. My resistances are very low and damage is only about 10k. Defense with buffs is maybe 10k. Life is 22k. My life on hit is about 600 though. There is a lot of room for upgrading if I hit the wall in Act II (which I certainly will with this gear).
Cleave is beautiful on shielding mobs btw. You're almost always hitting at least one of them (hitting zero can get fatal really quick when your life restore goes to zero along with it).
This is my build: http://us.battle.net/d3/en/calculator/barbarian#bWPVUk!VbS!YcZcbc
I find ignore pain is too short with too long of a cooldown to be worth a slot. So that is the "obvious" skill I am foregoing for Cleave. If the only way I can survive at all is during the 5 seconds ignore pain is active, then I'm just not going to play a Barbarian.
After reading the forum today, the only change I would make for now is changing Sprint - Marathon to Sprint - Run Like the Wind for extra life leech when running away.
Boon of BK is a luxury only because my life is to low to make much use of Relentless. I will probably swap later.
So am I dead meat in Act II? Any ideas for improvements?