You might want to try a website called Deja-News. This site searches the entire web on any topic ever discussed. All the postings you've ever made on the Internet will be found on this site. This includes opinions on modeling products. Punch in the names of your prospective trainer aircraft and you'll get varying opinions but after a bit of reading, a consensus will form.

I'm inclined to avoid the Avistar specifically because it has the semi-symmetrical wing. This generally means an aircraft that will fly faster than a flat bottomed trainer. It's just the nature of the beast. When it comes to learning to fly, fast is NOT good. Not that it can't be done, but learning to fly on a faster plane just makes it that much harder.

One of the best trainers, I've found in 35 years of modeling, is the Carl Goldberg Eagle. One of the reasons for it's success is that it was relatively light and could be slowed down so that the rookie could keep ahead of the plane. There are many others but wing loading is the key to a good trainer.