Sorry to bump, but when googling this (using Now bindings on a spiltboard) this thread is was one of the first, and most relevant, results I found when searching for info. So for future reference to help others:
In short, no, Now bindings do not work on a splitboard. Had my Hovercraft split recently (have since been out with a broken wrist so haven't gotten to use it since a test run, but that's neither here nor there), and expected the Now's - which I love, super bindings - wouldn't work (or, at best, much of the effect would be negated) but figured I'd check. The bushings end up sitting just outside the edges of the slider plates. Which means the hinge has a lot of extra space to "rock" into resulting in a huge amount of movement in the binding, and the bushing never contacting anything (plate or board). And also with the result that the forces are coming from the centre plate after you've rocked to the full extent. Very loose, not as responsive and a lot of effort.
Just have to keep the Now's on the solids - again, amazing bindings, highly recommended - and I'm throwing some older "normal" bindings on the split until I can pick up some splitboard bindings.
Anyway, just a heads up for anyone wondering.