The things i'll have to work on when i'm back in the firmware development :
1 - understanding and fixing the hanging notes i sometimes have when sending quickly midi notes.
2 - Put back sysex preset transmission - I have to find a smarter way to be sure the sent patch is exactly the same as the original one (internal floating point -> sysex is not straighforward).
3 - adding the "as played" arpegiator option (feature request) in adition to up, down, up&down, random.
The last one can be the more interesting for you. I have no idea how difficult it is.
You'll have to dig into mutable instrument arpegiator code : src/synth/Timpre.cpp bottom third of the file.
And src/midipal/*
To add the "as played" option in the menu :
src/synth/SynthState.cpp
Line 52 & 61.
Have fun :-)
Xavier