Well,

my Atari 800XL has only standard XL-OS and OS-B (switchable) but no QMEG-OS, so I cannot say anything about the combination of Hyper-XF and QMEG-OS. But as you may know with standard XL-OS it is not possible to have a bootdrive other than D1. So I am using a very simple trick:

- I use only partitions A, B, C, D but never M / multi
- if a program uses 4 disksides, then I simply use 4 diskettes and all 4 disksides of game 1 are copied e.g. to partition A on all four disks; all 4 disksides of game 2 are copied e.g. to partition B on all four disks, etc. When I want to run such a game, I simply boot the drive with open lever, choose the partition (A, B, C or D) and then reboot again (with ESC key) - so the drive is always configured as drive 1 and only sees this partition. When the game tells me to flip the disk, I simply throw in another diskette. Yes, partition or bootdrive change for multi-disk(side) programs is easier with QMEG, but as you see it is also doable with XL-OS... and 3,5" disks with 720k are still easy to get.

- the XF drive or better the Mitsumi or Chinon drive (or the 3,5" drive in use, e.g. Teac) is dumb, it cannot detect media change and thus it cannot detect density change; but Stefan told me in several letters that it is possible to add some small electronics so that the drive either detects the density automatically when you insert a disk (with a light sensor, with lever-movement or something similar) or when you press a button/switch; the electronics has to be connected to the FDC afaik (or was it the 8040/8050, I do not remember, since I am no electronics guy)...

- if you want to change partitions with a button or a (rotary) switch, this is also doable - there are several rotary switches available in good electronic stores; again, this button or switch has to be connected to the FDC (or 8040/8050) and as Stefan told me you can only have one of these things, either a) automatic density detection (or forced density detection by pressing a button) -or- b) partition change, but not both, since they partially require the same signals or pins (damnit, I am no electronics guy and the letter he wrote me was from maybe 2004, so I already forgot most of it)...

But if one of these two things (partition/bootdrive change) can be done via software/firmware, then one can do the other thing (density detection) via hardware, I guess...