The timing for the middle can get close sometimes if the team isn't proactive in calling out and watching for teleports. I've seen groups where no one calls out the teleport for 1-2 seconds after he teleports. This makes the middle's job harder since he has to cover a 180 degree area. The right can position himself to see all 3 front areas and is still in close proximity to the supercharge plate. I've done both ways and this way was no harder to explain or perform.

Distance. If middle is on the stairs between mid and right, they are closer than Right if he's on the yellow line. It's not as "natural" feeling, but when you get used to it, it's very fast.