I dont like how all i have are dots and that i cant reliably cast mind flay or some filler while moving.
What I would suggest is making mind flay reduce the damage all dots do by like 25% or something while you are casting it on the move. Remove the slowing portion of course, or have a glyph that makes dots do 25% less damage while channeling mind flay on the move but adding the slow back in.
Another idea is making mind spike like scorch and instead of removing the dots it would put a debuff on you or the target making all dots deal 25-50% less damage for 5 secs or so. It would be a 1.5 sec cast time and castable on the move. It may or may not buff mind blast.
The last idea I had was a cd that lets you cast only mind flay on the move for something like 8-12 secs and increases all the damage you do by like 10-20%.
1-3 min cd. That may solve priests cd and mobility issues at the same time.