more Nitro more power, that's the concept LOL, I have been flying Helis for almost 20 years now, and 1 thing that I like about using higher percentage Nitro is, that the higher the Nitro percentage is the tighter/shorter the tuning envelope becomes, it's more noticeable so tuning is easier to feel and hear when tuning, but you will find that is more noticeable with 2 Strokes than is with 4 Strokes,, the best way to test this is to first use a given percentage of nitro such as 5%, then test by going up in Nitro by 10% or 15%.. never the less, 15% is a good choice for planes,
you will have to lean your needle more when going down in Nitro..
Jim