I've used acetone at 3% occasionally but our winters are too mild to notice any affect. Actually I was wrong when I said I'd never used nitro because I've used it twice. The first time was with a K&B .15 in a rat racer for a state championship (which we won ) and later in a CL stunt competition held at a fairly high altitude where few of us had any experience with altitude. Australia is the flattest continent on Earth so most of our flying is probably at no more than about 1000' ASL. However these are the two occasions where nitro can help. Competitions where all out power is needed and to regain power loss because of altitude. For anything else, you need a bigger engine .

As far as tuning goes, nitro makes it easier for the simple reason that it's got a much wider range of tolerable mixture setting than any other fuel we use. The downside though is that it has to run far "richer" than any other fuel so the engine drinks it much faster giving shorter flight time at higher expense. One very slight advantage of high nitro (which to me means 15%) is that the higher fuel consumption allows more oil to flow through the engine which means manufacturers can put a little less oil in the fuel and still give the engine barely enough lubrication. However some companies (like Morgan) sell what they call FAI fuel (it isn't) with only 17% oil, the same amount as in their high nitro fuels. That's crazy because the oil flow is then too low for decent lubrication. Low or zero nitro fuel should have at least 20% oil.