Hi Smurf,
I've used movers for years and find they have definite advantages. You can make your existing lights more efficient by allowing closer placement to canopy and you get deeper penetration because of the varying angles the light takes on it's travels.
So depending on the shape and size of your room, a mover might be a good idea or not.
A definite yes on your yield being different for the two. If you were to add a second light...bigger yield. But if you compare a single light to a single light on a mover...then the mover wins.
They create a hassle with venting but not that much. You just have to suspend your ducting well so it can handle the movement.
ET