Just as an FYI: I used to run an OS FXi 46 on gas (it is sold now, but still flies in my club, so I know the engine is still doing its job and doing it pretty good). That engne still runs on the needles alone, no solenoid or anything.
Those engines typically are operated with an 11 x 6 prop, and they spin some 12K with that, a bit higher in flight.
With an 11 x 6 while burning gas, it "kinda works" but is pretty sensitive and "wiggling the needle within the same click of the ratchet" can allready make a difference. With that prop, ground RPM is about 11K or slightly below
I changed to an 11 x 5, which brought the RPM back up in the 12~12,5K range on the ground, and that restored adjustability. It still is sensitive allright, but that's the nature of the fuel (if you are going to burn half the volume of fuel compared to methanol, it is logic that one click has the same effect as 2 clicks on methanol, right?)

Same with my ASP 30 FS, which typically runs an 11 x 5 or 10 x 6 on methanol, but on gas feels happiest with 10 x 5, or the 91 FS that feels happy with a 14 x 6 on gas where it would like a 15 x 6 on glow.
A rare exception is the 52FS, which seems happier overall with a 12 x 6 even on gasoline. I am not quite sure why it does that. It runs very well with an 11 x 6 and is more powerful with that prop, but somehow it just runs "nicer" with the 12 x 6 and I cannot put my finger on it as to why.
So it is not a rule set in stone, but still more often than not, that a lighter prop improves things. Lighter props however, increase RPM, therefore power, therefore heat production, so you have to find the proper compromise (and maybe that is why the 52 seems happier with the heavy prop).

I did not run the equation, because I do not have the intake diameters on any of those engines at hand...