@Zp1:
I don't think Hisoka is going to be permanently wounded here. If anything, I think this is where it'll come out that Hisoka has some type of Nen ability that allows for regeneration of body parts. His long con back earlier in the series was making people think that he didn't have a way of regeneration (all the way up to requesting nen stitches, etc) as part of longer scheme of deception.
I agree. As a Transmuter, he has a 80% efficiency on Enhancement and since he already has two Hatsus (Bungee Gum and Texture Surprise) that can do both offensive and defensive actions, why not have a Hatsu that wouldn't take too much toll from the 20% deficiency.
Boost attack? Nope. Boost defense? Nope. Boost speed? Nope. Heal? Pwidi, piro dipindi.