@hibarimusic, the firmware build that I've uploaded has some bugfixes specifically for Owl. They were added after the old 20.3 release that was the last official build. It's probably better to use it instead of 20.3 and I was planning to make some new builds with more recent features.
And of course you will be able to switch patches from the device itself. I've ported that code from the old OwlWare firmware. Just press button, wait for a few seconds when LED starts changing colors and move first two knobs to select patch, then unpress button. LED would change color when different patch index is selected.
As for MIDI bootloader, it would allow you to install firmware updates and do some other operations without DFU program (from Chrome browser or by sending MIDI commands directly). It's not mandatory to use it with the new firmware, but it makes some things easier. If you want to try it, let me know when you have the programmer and I can upload bootloader image.
I think most people don't change firmware to OpenWare, that's why we don't have clear instructions ready yet. But it works better than the old one if you have the time and patience to update Owl.