I tried it out last night. Admittedly without the shield, so I could be missing...something. But what bothers me about the pony build is the width of the column. Too easy for squirrely elite packs to slip past it instead of getting knockback/stun locked. Even worse is when you get some on the side or behind you and you have to reposition. I was really excited when I read they added an initial hitbox to seismic slam(2.0.6 I think) so it would hit targets to the sides of the barb. Logged on, still disappointed. I really hate repositioning for one to two mobs because, in this build, that means 0 dps.
It's a shame zombie bears aren't a thing anymore. They solved this problem by having the bears start a bit behind the witch doctor. It was a small pbaoe followed by a short but wide frontal column. Even better if you stood next to a wall and sploited the bears into coming out single column for boss fights.