My .02 -
I feel like I’ve stepped through a time warp and am back in the 70s or 80s, when “event dressage” WAS truly different than straight dressage, and the tests required even at the international level of eventing didn’t require a lot of collected work. Back then, dressage wasn’t as influential in the final score and it wasn’t uncommon for someone to move up 20 or more places after dressage and you saw some very unrelaxed, unsubmissive tests.
But both sports have changed. The long format went away, a horse that could gallop all day was no longer a priority, and the influence of dressage on the final placings increased. You needed a horse dressage quality gaits to be competitive, even at Novice and Training. Even when I last evented in the 90s, lower level smurfs worked with straight dressage coaches. Heck, the riding school I worked for brought in straight dressage coaches for kids doing low level unrecognized events on leased school horses!
I will concede that there is some cultural difference; some straight dressage riders never, ever ride outside the sandbox and never, ever ride their horse in company. Eventing still requires a bold, forward horse that loves to attack their fences. But that’s about the only difference I still see. Good training is good training is good training, and everyone wants a horses that’s relaxed, rhythmic, straight and obedient to the aids. The truly effective people I worked with were remarkably consistent in their approach.
In re-reading the OP, I think the question behind the question is “How do I evaluate the quality of the training when I’m new to the sport?” That’s a VERY good question, and one that deserves some thought.
Here’s my contribution:
Is your horse happy in its work? Does it like iits job?
Is your horse progressing both in fitness and in skill? In other words, are there things that the horse used to struggle with that are getting easier? Or is that sticky left canter depart still sticky?
Can the trainer articulate their training program and goals to you? Do you know what they want the horse to be capable of in a month, 6 months, a year? Do they have a clear roadmap for you and the horse together, and do you, as the person paying the bills, understand what it is?
Does the trainer use brute force or coercion? Or are they patient and creative about working through resistances? Do they have a sense of humor about the training process?
Are they prone to quick fixes and gadgets? I’m not one to say you should never, ever do ________, but I distrust a trainer whose always looking for shortcuts.
So, OP, if both trainers you’re discussing meet the criteria above, they were both good trainers, just with different approaches. And they both may have been the right person at the right time for you and your horse.
If one of the trainers under discussion doesn’t meet the criteria, well, there’s your answer.
What criteria would others suggest for evaluating a trainer?