I would expect that the wholesale change from Darwin to Linux would introduce an amazing number of new and awful bugs. It's not like their development processes will suddenly be fixed when it's been touched by Linux.
On the other hand, it may work against us, having Apple involved in Linux things. I'm not sold either way - but I sit here, re-installing MacOS on two Macbook Pro's, both of which absolutely refuse to make a usable/safe disk image out of their own disks. This is such a frustrating conundrum, it feels like Solaris in the 90's. I can only hope something changes at Apple, or else I'm just going to wipe MacOS and put Linux on these machines. That is quite a watershed, imho.
I'm now trying to do a full update to the latest release, and see if it works beyond that point - but if it doesn't, the good ol' tarball approach is all I've got left.
I think Apple has some QA issues.