Melodyne has been very stable here. I haven't had a crash with Melodyne since last year and I use it on every project just about.
- I only use it as a Region FX.
- I DO bounce to clips after I make my edits (Render it) Because think about it...Why would I want to go back to the original clip ? If I am using region FX this means the original was not worth saving anyway. However if it ever got that bad, I have a back up just like everyone else in the Projects Audio folder. So bouncing to clips might be destructive, but the original is still there (unless of course you are using the "Clean audio folder tool" after saving your project).
- I don't over use Melodyne because I don't think that's what it was ever intended for. (but that's only my opinion).
I use it sparingly to fix guitar mistakes, Vocal errors and anything else that might need a quick fix.
if something is so bad that I would find myself using Melodyne on more than 50% of the track, I'd rather Re-record it

.
I also use Vocal synch and drum replacer. those 3 region FX are my best tools for house cleaning.
this is typically the first step I take in the mix down process.
My whole planning set up (though not really related to anyone's comment on this thread) is:
I never use Melodyne to be something I am not. So with this, I have been fortunate to have success with Melodyne.
What im trying to say is, I work in sections and render as I go. As I said earlier, if the clip is bad enough that I need to use Melodyne, then it wasn't worth saving to begin with. However like any good producer, I get ADHD and try to fix more than I should. but with being said, still been lucky and had no problems, no crashes.
To those who do have crashes, im sorry for your issues. Try rendering as you go though and see if that makes a difference.
Remember you still have a back up in your Projects Audio folder if you labeled your tracks correctly.