I'm developing a music engine for NES. What features, possibly missing from NT2 or MCK, would you like to see in the design? (This is a very open-ended question so that I can gather requirements from the community.)
Two of the most powerful (but still easy to use) chip trackers I've ever seen are Raster Music Tracker and Goat Tracker
http://raster.infos.cz/atari/rmt/rmt.htm
http://covertbitops.c64.org/
I think they set great examples of how to utilize frame-based effects in a tracked format.
That's what's really needed for good flexibility in a music engine.