I wrote a few patterns today on my new nanoloop 1.7 cartridge, which will be coming soon to our store. This video, although admittedly a bit hard to see, shows what you can do by rapidly switching between columns of pre-set patterns. I simply change the properties of each column a bit beforehand, either by modifying a bassline or by moving all of the notes up or down a few half steps, and play with the areas where I didn't populate all 4 banks in a column. Nanoloop 1.7 now mutes any channels that are empty when you load all the banks in your highlighted column, so it serves as a solo function of sorts. Very slick.
In the meantime, you can grab nanoloop 2.7 for the GameBoy Advance here!