I've tried Stunt .35's on 75/25 FAI fuel and they behaved just like this stuff. Kinda hard to start, super critical needle setting, significant power loss.
In the seventies everybody at the local club was using FOX 35s with 75/25 castor fuel.The same for every other glow engine. Nitro was simply horrendously expensive in Italy at the time.
No starting o behavior issues of any sort , almost every engine started first flick with usually a generous prime both in the carb and the exhaust. When mufflers became a norm, only carb prime ...sure when I tried 5% nitro needle settings became way more consistent ( I even used to cut a slot in the cowl to detach the engine without disturbing the needle for not to loose that "magic" setting found ). No particular power gain over straight fuel, as far 5% nitro. Maybe with more....
Also the we always used the original FOX needle ( even if whe had lot of cheap Supertigre needle valve assemblies ) because, once used to the strange one click=lean-two click=rich behavior, no problems of any sort.
When the fashion was toward ST 46, whe had a hard time to find again that FOX built in stunt friendlyness ( 4-2-4 etc .... )
I think your fuel is good to be presented to your closest competitor ( or...maybe actual FOXes are not the same as before, who knows...)