I know this is an old post, but here are my thoughts:
I went high envenom early so I could get lifebane to help with the pve, now I am considering lowering it to 34 so that I still have the highest debuff. and wait for 3 more RR's to get lifebane again. I need to try using the lower dot before I make my final decision, but from what I have heard the biggest diff between it and lifebane is the resist lvl being lower with lifebane, and slightly more dmg per tick. I may be a little misinformed as I have yet to test this.