ORIGINAL: downunder
As far as nitro content goes, so long as you don't use so much that the engine detonates then you can use whatever amount you like for running in or flying with. All engines (and I include even the little .049's) run perfectly well with zero nitro but nitro will add some extra power and possibly give a better idle. ASP engines tend to have a somewhat higher compression than most engines and that limits the amount of nitro they'll tolerate before detonating. It also means they'll handle zero or low nitro fuels better than some others. Anytime you change fuel types the engine must be retuned, even if you just change brands.
Thank you Downunder... I was hoping you'd jump in here with your expertise on this subject.
Grieke's ( spelling? ) article said the same about nitro content.
He advocated going to higher nitro ( 15% ) on smaller engines as a means to help idle and low speed stability, be he echoed that it is not needed.
Armody
At the Toledo show this year, Wildcat was selling their 10% fuel for $11.00 a gallon and 15% for $13.00/ga.
I picked up 16 gallons of each when I discovered that.