On
Aircraft - Home you have all the information you need about fuel consumption etc for the 912 ULS and 914.
I have a 914 in my Dyn'Aéro MCR-M and I see typically exactly the same fuel consumption as with the 912 ULS except for the few minutes during take off where I use the turbo. I have not yet investigated the high altitude performance though.
Best regards
/Bengt