Personally, I would stay with the self healing and keep toughness. You can take TWD for extra PRR instead of combat expertise or otwf.
Toughness is more then 37 hp depending on your race. It's 50+ for a human will all 3 tiers of racial. Personally I keep my tempest as a single target specialist, no cleaves, maybe hamsting or ic ranged at 24, haven't decided.
I have a kensai for cleaving, and massive dps.