I don't think the power role swapping would work. For one thing,k that is too wacky to be a regular game. It would have to be RM or BM.
But the other thing is that I just don't think voting would actually work. It would go two ways. The first way is that the day plays out like a regular game and then the voting is chaotic, possibly with lots of ties where everyone just has one vote. The second way is that the voting absolutely dominates day talk (I think we should all vote X for role Y because...) to the point where there is no room for scum hunting. The voting would only add extra choices to make that don't add much more meaning. As town, you would want to give power roles to people you think are most likely town EXCEPT that you wouldn't want to give it to someone you think will die.
Oh, and how would death even be handled? Will these roles always be in the game? I suppose it would have to be something like, if you die while you hold a power role, that role is lost. Except if this was the case, then that would FORCE the voting process to be pretty random and chaotic; if players discussed who they should vote in as a town PR, then that makes it trivial for scum to take them out.
And what happens if one person wins multiple roles?
But the discussion thing is the main point. It's hard enough to get to scumhunting when there is interesting flavour to discuss. If people had to bicker about who got to be the Cop, the days will not be productive at all.