Hi everyone, and thanks for your feedback !
My original question was more about the firmware to use than about the accompanying software, although I agree that it is an important thing too.
With the original Behringer firmware, I was quite frustrated that I could not use any button as a stompbox, i.e : when stepping on a particular button, it acts as a "patch" meaning that the led comes up on that one and off on the other ones. Therefore, you can't tell if an effect that you have switched on with the previous button is still on or not.
With the UnO firmware, it is a bit better as you can set 5 buttons (top or bottom row, your choice) to act as stomp boxes. But the midi message they send and their behaviour (latched/toggling or not) is fixed once and for all and does not depend on which "patch" you have selected before that. Therefore, you are force to using always the same CCs for instance and are limited to 5 out of the 10 buttons for this.
It would be great if all the buttons could be set to act as stompboxes and that the up/down buttons (used for selecting patch banks) could be used to switch between preprogrammed configuration sets for these stompboxes (is that what is called scenes ?).
Another good thing would be to be able to send more than 2CCs per button, instead of 5PC, just 2CC and and a note on, as I don't believe PCs are very useful for the ModDuo.
Is the Eureka closer to my wishlist ? Or is there a way to configure the UnO better ? Or is there another firmware that I don't know about ?
EDIT: Ah, and also, I have realized that when using a stompbox with toggle-mode off (so it is just 'on' while you keep pushing on it), two midi messages are being sent : one on the push, and one on the release, which makes it kind of unusable for controlling the "undo" button of the SuperLooper pluggin, as it results in undoing twice instead of only once ! I believe there should be a way to make SuperLooper ignore the every second midi messages on this button, or maybe I missed something about it. What do you think @falkTX ?