I did try warbling a few lip trills for interest. The notes are too fast for the manometer to follow, but for a lip trill E-G the indicated pressure settles at some 'weighted average' level that's a lot closer to the steady G mark than the E.
There doesn't seem to be that much in it. I've just done a quick check and for a high G, the Wild Thing seems to take a little (maybe 10%) less lung pressure than the mouthpiece alone to hold pianissimo. As the volume goes up, the difference magnifies exponentially: there's no way I can manage even a decent forte on the mouthpiece. I suppose that's where we get the leverage from the instrument's resonance....the second to see if playing the same notes on the mouthpiece alone require the same pressure.
No, I've not looked at flutter-tonguing yet.Grrrrrrr!