I'm liking where you're heading, and I think you did a pretty good job rounding yourself out.
Personally I'd drop Gruesome Feast, for something like Spiritual Attunement. Reason being, is because you have no pick up radius on any of your gears, so you probably wont be picking up enough health globes at a time to make the mana and damage gains worth it. In all likeliness I think it could pose as a death sentence if you go out of your way to pick up globes for the sake of dps and mana rather than healing. You could also pick up a thing of the deep and solve that issue rather quickly. Those globes love to drop in the most inconvenient of places, but that could just be my luck.
Severance is an interesting choice of rune for your spirit walk, though I think it would be more effective to go with Jaunt or Healing Journey. Typically when you find the need to pop Spirit Walk, it's to make an escape, not to rush into a bunch of enemies to do damage, and you're already using Vengeful Spirit on your Soul Harvest for some suicide run damage output.
In terms of gearing, I'd probably look to increase your vitality some more, and the easiest place I think you could get that is in a 200+ vit Zunimassa Chest.
Next up, I'd get a pair of int strong arms, with vit. I don't think you're doing enough damage to nuke things to warrent losing EHP for movement speed and IAS, and you're already too low in crit to sac the 4.5 for ias. Personally, I'm a huge fan of the EHP on Strongarms, and I'm sort of using mine as a benchmark for trying to craft bracers.
Edited by DonBukka#1245 on 2/23/2013 4:07 PM PST