It's been working well, the reason I run it is for the extra chance to add minus 1 to hit.
By turn 2 the deathstars are within range and most opponents don't unbind it since they're worried about van hels (or even curse if they're not running ++ saves) when it goes off on a 9+ then you've got a much higher chance of getting that negative to hit.
In terms of it actually causing the minus 1 to hit, I'd say it occurs 2 times a game on average, Which I'm ok with.
I find vile transference awkward to use since you need to be so close to actually get the heal. Since I'd rather have Arkhan sitting back I find that he isn't actually in range to heal from vile transference.
In the games that Arkhan has died I've still won because the opponent spent so much time taking him and the Mortis out that my grimghats were able to hold objectives and grind everything else out.