Yeah I've realised that with loops but they still serve a purpose from a compositional standpoint. Also assuming a midi converter can't be completely perfect it would definitely be easier to fix errors in a single loop iteration. I think the way to go is to just allow loading the same data into a channel or layer multiple times using labels though, there's no real need for looping at a note data level.
Also triplets shouldn't be a problem should they? Are the ticks not even or something? Admittedly I haven't really done much with triplets but if there's 48 ticks to a beat there should be no reason triplets wouldn't work.