It's commonly thought that SL is a bad talent for PvP, which I can kind of see due to nuking a pet also damaging the warlock quite heavily. I was thinking earlier about how it can be used as a sort of defensive stance. If you keybind SL and only activate it when you are being swapped to, your healer can beacon/hot up both you and the pet and you get a split of the pets healing as well as your own. Or keeping your pet and healer behind a pillar and healbombing the hell out of the pet to keep you up. The only downside I could see with this is when a team dots up or cleaves both you and the pet.
Basically toggling it on and off to make the pet take your damage, but not make you take the pets damage.