Ummmmm, you can OBVIOUSLY do a decent mix up after dice oki (low, high, or cross up).
You don't have to GC out of the oki, however even when "done right" they can still escape it by GC.
Problem is: if player is using something like Evil, they can teleport out on late tech.
If player is using Wind, using GC will push you away, prevent any kind of mix up (so you would need to bait the GC).
Once you guys start playing the game, this should make more sense to you'll (or I hope it does).