I have auto save set to auto save every 8 changes I think. Something like that. It works great for me and has saved me a few times. But when it goes to save, I always forget and wonder what it's doing.
Like if I'm messing with PX64 on a drum part. I may turn the same knob on the Shaper many many times. And when it auto saves the screen reverts back to the compressor. And I have to click something agin in the Shaper to get it's graph to show. PITA but I live with it.
There's other things I've noticed about autosave that's a little anoying, but like I said, it's saved me many times before.
I don't use "save every XX minutes" because I always forget that I have it set to that and There are certain things you don't want to be in the middle of and the time comes up it will save no matter what. But with "save every 10 changes" it won't save until your done with the thing your doing, then it saves right after.