Thanks for your take on this Watson. I like it.
I think grapples can be managed, but they really aren't effective for the kind of movement we are talking about. The movement of a grapple is almost like a side effect. If you're grappling something, then your primary desired effect should be the block, not the movement.
I never liked Rick Neal's solution for the same reason Sanctaphrax threw up for using the athletics rules. It's too easy, and makes it much better than simply moving. It's all too easy for a submerged character to throw 8-10 shift spells around. With that in mind you'd have mages throwing themselves (or others) across the map with ease. We're talking complete control of where most targets are at any given time (especially if you allow them to hit multiple targets, either by splitting shifts or zone-wide evocation).
Anyway, I really do like your solution Watson. Seems like it works.