Op, we're in the same boat!
My friend's a barrel racer/rodeo-er. I'm more into western pleasure and English riding.
We often ride together (in the same arena). She has a gorgeous new barrel horse - I think she said I was a $12,000 1D/2D barrel horse - they win a LOT around here.
Anyway, We also sometimes swap horses. I'd ride her amazing horse and she'd ride my 13.3hh POA gelding who's trained to basically just be a great all around pony (one who's decent at anything you want him to do.). There was a barrel pattern set up in the arena, so obviously I wanted to run this amazing horse on it! So I did. The horse was truly an awesome barrel horse - but he was completely autopilot. I could have just sat there bridleless, clucked and spanked, and he would have run a perfect pattern. She was riding my spunky little guy, and he couldn't get him to stop rearing (which I've never really had a problem with). Turns out she was completely balancing her weight on the reins, which he is NOT used to (we typically ride on a loose rein.) so I told her to loosen the reins a lot, and he acted fine, but she went to trot him and she was really bouncy on him, so I told her to post, and she didn't know how.
That's my experience with spoiled riders! :)