I don't think you will be seeing a batterskull on a pit dragon gaining you a crap ton of life very often as RPD will most probably be sent farming, but it's possible. I don't like the 5cc, at 4cc it would be ideal (but that would be broken @ 4 mana). As the last card in your hand, a 4/4 vigilance lifelink is nothing to laugh at. It's like a colourless baneslayer, that doesn't fly. It will most probably be sent farming as well. But Even if it does, ANY topdeck Simian spirit guide, priest, revoker or magus of the moon becomes a huge threat. 6/6 vigilance lifelinkers win games. Just ask wurmcoil engine.
But right now it's fighting slogger and Moltensteel for slots. I still prefer moltensteel because that 1 mana difference is huge. But if tribal/midrange is the way decks are heading with less combo, Batterskull might be a better choice. BTW, batterskull 25 USD sold out on SCG? Man they have to stop printing stuff for caw blade, it's annoying. Can you imagine this with stoneforge? You ninja it into play with SFM and then bounce, repeat when the germ dies.

