Are you referring to the Evolution engines? If so, I dont know where you get the impression they are not adjustable. True, they come from the factory with a set RANGE of adjustment, but that range is adjustable also, in the event that the engine doesnt run well within the factory set range. I had to adjust mine the first time I ran it. Aside from that, the needles adjust just like any other engine. If you're not talking Evo's, I apologize.
ORIGINAL: Scar
ORIGINAL: mikie_mays
Which is the best trainer in your opinion?
I think, for the money, the best purchase is an RC flight simulator.
If you buy a plane with an engine, I would say to stay away from the ones you can't adjust. (You want to learn how to adjust your needle valves, right?)
For extended use, I would stay away from the one with the wing brakes and dams. All the others will fly fine, expecially if you have an instructor with buddy box & cord.
Otherwise, no preference. Good luck,
Dave Olson