Well, what I do is place the aux switch below the Factor on my pedalboard. Then, Bank+ (on the pedal) is directly above the 3rd aux switch, which I set to Bank-. They may be on different boxes, but having them one above the other helps me keep their functions straight.
And yeah, unless I'm missing something (nowhere close to the first time I've done *that*)… I can't find any way of reprogramming the functions of the Factor's switch, other than switching between Bank and Play modes. I agree, though, that it would be really nice to do that, but I've also heard that it would likely cause additional confusion among the users.
My vote stands for being able to change the functions assigned to the switches on the Factors, too, and not just the aux switches. As discussed previously in other threads, I think it would be nice if all Factors worked the same way, too. (Space has 1) active/bypass; 2) preset+; 3) preset-, instead of the PF, TF, MF having 1) preset x:1; 2) preset x:2; 3) Bank+.) I can see benefits of both paradigms, so I really don't care which, but it would be nice if all 4 Factors worked the same.
Sorry… that was apparently my rant for the week. 😉 I'm much better now…
In all seriousness, please do let us know what your eventual solution is. There are a lot of great people on this board, including several Eventide people who are very helpful, who I'm sure can give you several more ideas!