i'm totally in two minds about such things.
cos, unless you've got a really good machine, you can't really change time signatures within a tune, or have any kind of intuitive speeding up/slowing down.
it also takes away a lot of the visual aspect of a live show. kinda feels like miming.

of course theres advantages: one less band member to sort out, WAY easier to move around/set up...

i wish i could have seen Big Black live to see whether it works or not.]

drum pads are a different matter entirely, and i reckon building them into a normal kit is a great thing.