I don't object in principle to Maul=Grievous. I just wonder what he did for the ten years after TPM and during AotC? This would have to be explained as well as his rescue/reconstruction and I can't see there being enough (if any) appropriate material to do it without it being really scrappy. It's always worth a try, but I think you should be prepared to lose the idea if the execution doesn't live up to it.

Infodroid - watched the new clip. Better, as the WS and OTS shots give it a more natural feel than the other one. The lack of Maul material shows, though. Depending on where you end up putting it in the storyline, you could try playing most of the scene without seeing Maul until the end, thus using that one shot as a reveal. This would work if it's the first time we see him, but not if you follow my earlier suggestion about Tatooine being his first appearance. Overall, I prefer the latter. The prequels have a lot of telegraphing (we're going to do this, now here we are doing it) which is not like the OT. We don't need to know what Maul is up to or who he works for until he fails to get Anakin and then reports back.