RE: ABC vs. ABN
I honestly think the TTpro 40 is a great deal for the money, even at 99 bucks. Yes, I have more than one, but I typically have more than one airplane set up at a time, too. I do NOT spend a lot of time testing, comparing, or running engines. I just don't see that much difference between them. The ONLY trouble I ever had was that steel caged bearing letting go at the wrong time.
You don't even need 18 dollar bearings.. I have used stainless rear bearings from RC-bearings, something like 6 or 7 bucks, and they've run just fine. Wish I would have changed that one BEFORE it let go, that's about my only recommendation for the TTPro. Take a look at that rear bearing, and if it's the steel cage type, change it sooner rather than later.
And yes, the price of the engine is one of the things that helps attract new folks that have not yet been bitten by the race bug. That, and the fact that it has a throttle, if they decide NOT to race, they always have a really nice sport engine that can be used somewhere. I know around here (Kansas City) that there are several folks getting their feet wet in 424 that would NOT have started had the engine of choice been a 200-250 dollar item.
But - once they get their feet wet and find out how much fun you can have racing, several have gone on to own Jetts & Nelsons. Still, our best turnouts here are the 424 races.