Some feedback, looks like the update to 3.2.6679 fixed the slow down issue on files with Samplerates lower than 44.1kHz (it quite possibly was in before this patch, but the previous patch I had running before was the first version that enabled playlist folders in exported iTunes xml files (3.2.6660 ? maybe ?) and on that I still saw the slow down happening).
Also 48kHz seem to play at normal speed now as well.
There is a few 96kHz files I have, and on all of which, when attempting to play, Musicbee throws a pop-up, claiming this still:
Unable to start playback
Not a big issue for me, just wanted to mention it.