Drum leakage can be a good thing. A bit of snare rattle in the kick drum can work wonders.
It can also be a royal pain in the arse. Try using drum replacement (eg drumagog) on a track with excessive bleed from other mics for example or re-timing an errant drum fill that is full of shit from other mics.
Am I going to buy this? No. I so rarely work with live drum recordings these days. For folks that work with live drums a lot I could see this being a useful tool.
Mind you, this fella doesn't have a problem with drum leakage:
So I guess it depends what type of recordings you are trying to make.