Some engines aren't happy with it (ex Fox Stunt .35) due to a very low compression ratio. Any engines with a high enough compression ratio seem to tolerate it OK. It sometimes requires switching to a hotter heat range plug; the Enya #3 or Fireball "hot" seem pretty good with 0-nitro.

Top end power will of course be off some compared to running nitro, but unless a plane is marginally powered to begin with this is not usually a concern for ordinary flying.

Needle valve setting will change a bit. My experience has been that you tend to turn them in a tad compared to nitro mixes. The power/rpm will drop very quickly and noticeably if you've gone too far and it becomes too lean. i.e. the "sag" comes on much faster than with a nitro fuel.

I've been experimenting with various methanol/oil mixes this year. "Standard" FAI fuel is an 80/20 mix, but I've mixed 75/25 and 72/28 for initial break-in purposes with varying proportions of Castor/Klotz. An old OS FP .35 seemed particularly docile and easy handling on a 75/25 mix with 50% of the oil package being Klotz the rest castor. Three chokes to prime, and it would start on one flip 95% of the time. That FP .35 was using the Fireball hot plug BTW.

The G.34 is still on the original factory plug and has around 3 hours on it now, all running no-nitro. It too is generally a "one flipper".

Some engines, generally foreign ones intended for FAI competitions, are specifically intended for no-nitro fuels and will exhibit predetonation tendencies when run with significant amount of nitro, although there was an earlier batch of Fox .74's that had higher compression ratios and would show predetonation with 15% nitro fuel.

The appeal to me is Klotz/Castor/Methanol are available locally in Ft Lauderdale in 5gal cans, nitro seems harder to find unless you want to buy $2000 worth at a rip.

As a general statement, it seems the larger the glow engine, the more likely it is it will function with no-nitro.