Interesting debate here. First, AA5BY, I'm not quite as old as goirish, but I'm approaching 63. My reaction times are ok, not what they used to be nor are they as bad as they could be. I started RC about, oh, 8 years or so ago. And, I used to compete with handguns and rifles, so my hand-eye coordination is probably better than most.
I trained on the Nexstar and didn't have much trouble with it at all. First of all, my instructor was one of those that taught me that there was a stick called a throttle and that it moved proportionally, and that it was not a switch. So, I learned how to fly the thing as a trainer. I later took off the gizmo's and started to fly it as a sport plane. So, you are right, it is a dual purpose aircraft, and I enjoyed flying it.
One of the most difficult planes I flew was a "true trainer" as you would describe it, and it really tested my abilities to fly the thing after flying pattern planes that flew like they were on rails. But, I didn't know there were such things until I started flying them, so I was pretty much used to flying my trainer/sport aircraft and dealing with their handling and their capabilities, however lacking. I moved up slowly, all the time learning that the throttle was still proportional, and how to fly straight and level, until I moved up into the more precise hardware. But, I went back to the trainer and flew it one day.. learned how much I had "un-lelarned" and had to spend some time learning to fly the trainer again. Odd, but true.
Anyway, Gray Beard.. as you can see, I liked my Nexstar, but, hey, some people liked the Nash Rambler too.. ha.. oops.. but if it's the only thing you know (as a trainer and to a trainee, what else do you have to compare with), well, it's what you have and you learn on it.
I bought a "club trainer" because the club didn't have one. It's and Hanger 9 Alpha ARF. I put it together and put an OS .46 FX I believe it is, but have not yet maidened it. It was a replacement for another trainer that I planted one day last year. Long story, but suffice to say that it was truly pilot error. I got to love taking out the trainer and fly it just to relax and to step back to basics.
Aaaanyway, that's my story, and I'll stick to it!!!
CGr.