Could it be possible to access to change the pattern of only one track ?
For example, you select the track you want to change the pattern and while holding the track switch you choose the pattern.
In this condition, you will have the same behavior as the historic Rebirth :
4 fully independant instruments in which you can choose in between the 192 patterns already stored.
In this case, you keep the memory organization that you have today : no more pattern have to be saved, but you only load in RAM the part of the pattern you have choosen.
I do Believe this is not a big change in the way it is programmed : I have built my own sequencer in the past (on ATMEGA 2560) and each pattern was stored in a table. When Calling a pattern, it was just a change in the pointer to the address where to read the data which where transfered to the RAM at the time when I need them.
Maybe this will help you:
It’s possible to recall a single track from a pattern into RAM.
To do so, in LOAD menu, hold the track button which you want to recall, while pressing a pattern button that you want to recall the track from (also see Manual page 25).
Unfortunately this doesn’t work for storing patterns (you always store all 4 tracks), but maybe it still helps you in the way you want to work.