Hey Rory, it's been a while!
I was using soundfiler on Cabbage beta 7 I think. In the documentation it is mentioned that the channel identifier takes in 2 arguments, the starting sample position and ending sample position. I am able to replicate this behaviour on Cabbage 1. But on Cabbage 2, channel 1 gives the difference in position between start and end, and channel 2 outputs zero all the time. Has the channel mapping changed?