Dismember is not a board wipe at all. It's targeted removal. If you meant something that gave all creatures -5/-5 then yes that would be pretty sick.
I think this card is OK (strictly better than infest), but I don't think it's the board clear that mono-black needs in standard. It is better than Shrivel that has been the sideboard tech against MonoBlue and White Weenie and it will clear an army of Satyr tokens from Xenagos. These alone will make it worth playing, but it's no Damnation or Mutilate. It doesn't do a lot against GR Monsters, Selesnya agro, or an opposing army of pack rats, which are what, in my experience, MonoBlack suffers the most from. I guess it does work against MonoRed Devotion, unless they have the turn 3 hammer...