I haven't read every post here, so I'm sorry if I'm repeating something. But part of the reason why I chose my current trainer is her emphasis on flat work. She in no way would call it dressage, even though she is doing dressage movements with her horses. She rides/shows on the A/AA circuit. Watching her school one of her more advanced horses is just lovely. She works on leg yields, shouders/haunches in/out, extension/collection. She has taught me more about bending a horse correctly and balancing through a turn than anyone else has. She has helped my AQHA HUS horse (who still does the class in the same frame), push from behind more and use her body more effectively, while staying in the frame needed for the class. When I compare her riding to other trainers in the area, she seems to be sort of an anomaly (sp?) Sure, there are a few that do this, but not that many. But the brillant thing is that she teaches her students how to do this as well. And to me, this will help us get around those courses so much more effectively, and softly, than I would have otherwise.
Now, why she won't call it dressage. Because she stays in a forward hunt seat position, maintains the same frame. Yes, it is the movements but it's not what she considers to be classical dressage. Yep, it's probably splitting hairs, but to her it is just good flat work.