FWIW, I've asked someone who runs it what the average life loss/gain is from Blood Artist is and he said about 3-5. I'm testing it to see if my data mirrors those results and to see that's worth it (and I'm hoping to get a lot of data this weekend at the STL SCG Open.)
I used to write cube articles on StarCityGames, now for GatheringMagic and podcast about cube (w/Antknee42.)