Hey Zack,
I'm pretty sure you could use it. The only disadvantage with the Rm4 FS would be that you'll be a little bit limited to controlling individual effects/presets since it only has 4 switches.
You can still set it up to have all the 3 channels in your head to be dry when clicked on the 1st time and then make individual presets in the xpression with whichever effect you would like to add for when you click on the footswitch of a individual channel for the 2nd time.
This way you could assign Reverb/chorus for your blackface or a long delay for your XTC and so on...
I bet you could even make the last switch a wet/dry master for all the others if necessary.
I'm not incredibly midi savvy so i hope i helped a little bit.
Mike