yeah I think 25% is the best compromise in turns of performance and engine life.
i promise you that there is no drop in engine life, just gains in performance. the only engine life drop you could see is that it might bite the dirt a 1/4th of a gallon sooner.
nitro has nothing to do with engine life, its the oil type and oil percent that effects engine life..
grow some and get the 30%.
most ppl run 20% because of EFRA...