This mixer sounds pretty cool. I read their manual and they talk about using their mixer for both elevons and flaperons and how to set up for both. They explain how flaperons differ from elevon mixing in that the flaperons start at a neutral position and only go down, just like we're talking about doing instead of up and down like elevons. So, while it'd be pretty expensive, three of these mixers would give you pretty much complete authority over all the controls and have them pretty much behave like you want.

I've been thinking about it and can't really see a reason why it would hurt to have the LE flaps (and/or TE flaps, too) reflex upwards with down elevator. If I were flying inverted, I'd want the same sort of manueverability available as when I were upright. I wouldn't want it to be super-manueverable when upright and relatively un-manueverable when inverted. But, if the mixer is able to inhibit the reflex, then it sounds like it might be the ticket to be able to make the controls behave either way.

Combining these mixers with the on-board transmitter mixing opens up a ton of possibilities. For example, by slaving the aux channel to the flaps channel using the transmitter's programmable mix, you'd be able to couple and decouple the LE and TE flaps in flight with a flick of a switch. So, if you wanted max manueverability mode, such as you've seen in the video, you would decouple the flaps, then twist the aux channel knob to dial in some LE flaps. Then, when you're ready to land, you'd flick the switch back to couple the flaps again, then twist the flaps knob to lower both the LE and TE flaps simultaneously. You get the idea.

Dan