RE: NITRO QUESTION
it's more dependent on the oil content in the fuel. If you go from like a 15%nitro/20%oil up to say a 20% nitro and 10% oil it MAY wear the engine faster, but it might be negligable. Lots of LHS are somewhat dishonest in that they'll feed you an old wives tale to get you to buy the "better" (usually more expensive) products.