The textual MML format worked very well for rhythms and experimenting with sound parameters, but I never warmed to it for writing melodies. If I play with NES music again in the future, I think I'll write my own player routine and compiler instead.
Also, note that due to the steady deterioration of the Linux platform, recording the above NSF file to create the mp3 took me over an hour, and then only because I gave up and used Windows (although I understand the trend is to make this sort of thing increasingly painful there too). If Debian still provided me with xmms and the NSF-player plugin, this would have taken less than 30 seconds, and I wouldn't be ranting to whoever will listen about how I want to boil the ALSA developers alive in hot oil.