There is another thread on this subject here https://www.guitartricks.com/forum/thread.php?f=24&t=47194

I agree that it is what is needed. 0.5 is unuseable and all the speeds faster than x1.0 are pretty pointless.

I imagine though that GT are using a bought in media player and so probably alternative speeds are not available. They should do something about that as 0.75 would make learning so much easier with some things.

I wouldn't hold your breath though