Well never say, never.
Thanks to Anders and Olle, Frederick from Elektron for helping out with this one.
It turns out you can force the Elektron devices to communicate at a specified speed using the following SYSEX message:
MIDI_SPEEDPUSH
0xF0,0x00,0x20,0x3C,0x00,0x00,0x20,SPEED,0xF7
–
No celebrations just yet. Long SYSEX messages such as Kit and Pattern dumps are not being received correctly and I had to re-enable Active Sense to get this hack to work (so all those bugs are back). MIDIClock and short SYSEX is working though, surprisingly.