Actually, having taught a couple of guys to fly gliders when they took up R/C. And then taught them about power when they decided to make that transition a couple of years later. And taught guys to fly power when they took up R/C.

Yeah, bottom line, learning to fly an R/C airplane with a glider is an excellent idea. And it doesn't cause any problems later, but as a few experienced guys have mentioned, it actually makes the move easier. Nothing to unlearn at all. Even moving from a Rudder/Elevator glider to a full house power trainer would not entail any unlearning. R/E setup is with both on the right stick and flies almost exactly like most people fly with full house, put some left into the stick with a little elevator to turn left. The dihedral that WILL be there will roll the glider left. Looks pretty much to a beginner like he'd given the sucker some left aileron. Nope, nothing to unlearn or relearn. Nobody thinks "rudder" when moving that right stick, they think "roll into the turn".

I'd suggest that the flyers I know who have glider experience, be it from their learning R/C with one or later into the hobby, are absolutely better flyers hands down. And the couple of guys who I know who learned R/C with gliders who went into power really head and shoulders above the average power modeler. Problem with that observation is I don't know but just those guys who did that. Small samples etc etc.

I also never met a beginner who wanted to learn within a time limit, or one who needed to learn in the shortest time possible. So the idea that starting off with a glider is somehow bad from an efficiency standpoint escapes me.