In the live video I ve seen you triggered a pad many many times while shifting start point. I think it would be nice to be able to keep the pad pressed when skimming through the sample with the data wheel.
Otherwise I am impressed by the video and what you re doing in general. Must be really tough to manage everything. Respect.
What you are asking for can be done by using the quantize/note repeat button. Otherwise if it did it automatically it would be a mess (not everyone wants the sample starting over every time you adjust a start point.)
Right now this works the same way the 1200 does.