As long as you only sequence in the digitone, I don’t think there will be any problem. because the triggers are coming from the digitone…
problems start when you combine sequencing on digitone and ableton. turn on the metronomes on both digitone and live, and you’ll see what the problem is. you can try compensating this, but the midi jitter is so bad (in my experience, with my equipment) that it really didn’t work.
slaving the DN to live through overbridge will be the best you’ll get I think. but I guess you don’t want live to be master.
but again, as long as you only sequence on the DN, and not in ableton, and you don’t use any rhythmic audio clips in ableton, I don’t think you’ll have any problems.
I don’t know reason, and it’s midi sync quality, but another midi interface like the one you mention will not help this at all, because the problem is in the software. I don’t understand how ableton didn’t resolve this by now. I synced hardware to traktor before, through a NI controller, and ableton was slaved with link. the sync was as tight as I could wish, so it is possible!