I'm doing a very large orchestral template now, with 20+ kontakt instances.
I left one VSL instrument at 6th place the firsts 5 kontakt instruments. I think that there's a problem in that particular position.
No problems for now. Every instance I add I save a MIR project with incremental save (now I'm to 39 saved). I don't fully load every instance with articulations, just one or two per instance.
Incremental saving let's me to revert back to the previous saves, and every 1-2 saves I close MIR and reopen and see if it opens the project. Every 10 saves I reboot my PC and see if MIR opens.
If there's a problem, for me, it's not related by kontakt itself, but with generic 3rd party plugins. And in my opinion, it's totally non-related to protected or unprotected libraries and even less to 32 bit or 64 bit libraries (since you load the samples and the original kompakt player is totally absent in this workflow).
I' m fairly happy for now but I'm very very cautious about everything I do, in MIR. Like walking on a mine camp :-) (sometimes it crashes at loading the project, but I insist, and it opens)