CS... I wouldn't worry too much about the bad block remapping. XNand Healer does a very nice job of it. Also, there will be a rare (I've had 2 so far) instance where blocks shouldn't be mapped to the end of the NAND as usual. So to really make the remapping option perfect you would need to have a start or end block option and have it map from or to said block. I've already talked with the XNAND people and they're looking at it since they haven't had an update in quite a while, but I don't expect anything soon (if at all)
Anyways, lovin the app!