I haven't had any problems yet, nor did I on previous bikes with ABS & DTC. Mine is not EU spec so maybe they have more stringent electronics oversight for Euro 5 emissions, but typically all of your big brothering depends on the IMU and tone rings at the wheels to make calculations.. DTC, ABS, DWC, DSC are all just looking for differences in wheel speed; "lean sensitive" ABS just changes application of the pump depending on angle using the IMU, and so does the rear wheel lift control (I forget the acronym) to keep you from doing an endo.
As far as I know the only time the ECU intervenes motor-wise (not driven by wheelspeed differences) is your QS and RPM limiter. QS is set up to operate within a certain RPM range for blipping downshifts but you can upshift right above idle if you want, neither one should care about wheelspeed, drivetrain speed, or gear.. redline is redline whether it's 1st or 6th gear. I'm curious what their issues were.
I would say start with -1 F and see what that gets you. Heads up that involves removal of the left side rearset but I would argue it's quicker and less expensive than changing out the rear drive to a quick change style.
$20 and an hour of your time will get you a decent change in the bike. Funny they asked your intentions when they were doing it themselves!
