lifesteal and LOH are different.
LOH are way more effective.
Why need to block?
I'm not saying you can't use shield & block.
If you need shield, at least, you need to increase DPS.
Basically we see 2 types of Barbs that do well in A3/A4.
Barbs with high DPS (with or without shield). With REND, they are like boss now.
Barbs with WW-Tornado, they kill monsters in bulk like boss.
Both builds are offensive type.
Barbs don't go defense anymore.
P/S I give you another option, Barb with high LOH (you need at least 2200LOH + 20K DPS).
P/S Just to give you an idea, with high LOH, I can kill Ghom without Overpower (CA). Just stand there and whack the fat fart.