Bailey, I used to frequently go to Aveda salons. The company was founded here in Minneapolis and my mom used to take us to the Horst School [named after the founder] when we were kids for cheap cuts. That was the first salon to take my curly hair seriously and taught me how to condition and style it so it would be curly and not frizz. I went to the school for a cut when I was around 20 and they used diffuser on my hair — which was quite a novelty to me. That was about 16, 17 years ago.
A lot has changed since then. Around here, they're called "Juut" salons now. And of course Aveda is owned by Estee Lauder. But I've gone to Horst/Aveda/Juut salons throughout the years and have always been impressed.
As far as the training goes, I'm not sure how exactly it's run, but the Horst School is still here, a different building from when I was a kid, now near where I live currently. I don't know if all Aveda stylists go through that school/training. Some salons sell Aveda but that's it, some are actually Aveda concept salons. I'm gathering you're talking about the latter.
I also worked at an Aveda salon briefly while I was in college — as a towel girl, haha — and I was very impressed wtih the thoroughness of their standard employee training and development. Even for someone like me, who was mostly going to be making tea and drying towels. The best part was I got a spa service as part of my training — a massage!