I have a couple of these (not flown one yet) but have been experimenting with setup. The manual talks about using CH ID 6 for a second AIL servo and that you can re-use channel 6 for flaps (or whatever) if you split the signal upstream of the AXIS.
So far it looks like you can do the same with CH ID 7 which the AXIS uses as a second ELE servo channel. So it seems you end up with two extra channels for free. Interesting...