Yep, DGrant has pretty much said it all. I was in the same dilema about 2 years ago. If you're planning on doing a lot of flying, especially consider his last statement-"Cheaper to operate." Not only on fuel savings, but less cleaning up to do, less paper towels, etc. Buying gasoline at a buck thirty beats the cost of nitro any day. It initially grieved me to pay the bucks for a Brison 3.2, but I was certainly glad later. I'm sure it applies to the other engines in this price range also. We had 22 flights on this engine before we ever made an adjustment on it. It performed just as advertised right out of the box. Fortunately, there are a lot of planes made to fit the engines available today.
Randy