I have reported it before but didn't make a big issue of it. There seem to be a lot more reports of needing to restore a backup this year.
I have reported the Windows File Associations a few times as well. The upgrade process just doesn't seem to address that issue at all for me. Also quite a few reports of that nature this year.
Nothing special about my installations, except perhaps that I usually have two versions of MC installed when I upgrade. So MC22 plus MC23 when I upgraded to MC24. Main library on the HTPC is in the default location, so should be found. On my client I use a local library as the default, in the default location, so that should be found. Backup location on the HTPC are standard, and custom on the Client, but both as per Options. The backup location for multiple libraries is common to the PC of course, so all backups are in the one directory, mixed together.
Half the problem about catching it and reporting it is that it only happens once a year, and I only do two upgrades on two PCs. Replicating the problem to identify the cause would be a real pain, since I would have to uninstall all MC versions and licences, then install say MC22 and MC23, licence them then upgrade to MC24. I would probably have to start playing around with VMs, or full backup and restores of my boot disk, in order to identify the cause. Your crack Beta Team can only do so much.
PS: Also, there is the issue that the upgrade process usually isn't settled down at the time the Beta Team members do the upgrade. There are often a few things left undone in early versions. I waited until I think MC24.0.5 before upgrading this year. Same issue.