I've had this Disaster Area DMC-3XL MIDI switcher (Gen 3) for several years now originally using it for my Atomic AF3. Never hooked it up to my old AX8 as it had enough switches so it was put aside gathering dust since 2017.
When I got my FM3, I decided to try the switcher for scenes. The unit also has an expression jack and on the side, an expression roller which I have yet to configure.
One amazing feature with this little box comes through with a firmware update 1.62 which makes this box a keeper. They have implemented a hold function which really adds to the functionality. After some figuring out how to program the unit to send MIDI changes, the unit is set up as follows:
Left tap: Previous scene
Right tap: Next scene
Left hold (2 seconds): Previous preset
Right hold ( 2 seconds): Next preset
Works like a charm!
The beauty of the firmware is you can program to toggle values, momentary, or one single command (which I have). The expression jack in the back of the unit is not assigned yet nor is the expression roller on the side. Kudos to Disaster Area for "pulling a Fractal" and updating the firmware.
It was originally intended for my 3 button Atomic Amplifire at the time and a good match in red but is also available in black. There's a great YouTube video from Disaster Area which explains how use the new features of firmware 1.60 and configure. This version 1.62 is just an incremental update but pretty much the same.
I find this way more usable than my Boss FS7 and can use 2 expression pedals on the FM3 & not sacrifice a jack. There's also an expression jack on the DMC-3XL and even an extra "multi-jack" which is programmable for MIDI or expression. I may get to trying those one day.
Great little box as my FM3 can now have any layout or performance page I want and can still quickly switch between scenes and presets. Also set the default scene to #2 on my presets to have one tap access to a different scene on the left and another on the right.