Yes, it is straightforward. If you import a loop, just set it's BPM and do Reset Grid to set up a beat grid for it, then assign it to a patch with Tempo Sync on. For internal resampled stuff, the beat grid is set automatically. Also, the quality is very nice, not as great as with some pro sample editors, but very usable and it's realtime after all - this means (at least on the Fantoms) you can control the timestretching with an LFO or an envelope or even a knob, plus beat-keeping realtime freezing is possible (again, not sure if 909 can do it like the Fantoms).