I was just coming back here to report that using the RLEN parameter for directly multi-sampling other synths works really well. I’ve put some banks of chords in the sequencer, then recorded different patches on my Nymphes, really fun to play.
Only hiccup I’ve run into, making a chord pad bank, is that it works best to have zero attack so the record arm threshold gets crossed right on time. Then DT can provide the amp envelope and extra filtering as needed.