You need higher dmg mitigation, LS by itself isn't going to do anything, just like LoH isn't going to do anything for a CM/WW with poor dmg mitigation. I gain life when I hit a reflect pack on MP10 with 4.5% LS, 3% only allows me to breakeven.
So the solutions to RD are as follows: get better AR and more HP, which will cost a fortune AND get a 3% LS weapon...or just get a cheapo LoH/LS weapon and use it only when I encounter RD.
This is why BM is stupid. If it can't address just one affix you MIGHt see in a run, then it's not up to snuff, imo.
(My mitigation is fine otherwise. I don't die much, and my runs are generally very fast, very clean, very efficient in the mp3-4 range. RD is the only issue.)
You can run BM if you have high dmg mitigation, your dmg mitigation just isn't high enough. I think aimless was running perma archon on MP3-4 and he was doing fine with just BM.