Time in the water, solid skills to manage task loading, the ability to learn and revise the theory, and the ability to 'tune' your gear to work for you, these are a few things to make you a good technical diver. A good instructor (but also one the compliments you) and a solid amount of time and effort, you'll be fine. If you don't like to be taught, don't use an instructor that only likes to teach, find one that is good at coaching and mentoring you. You do your best learning away from your instructor after your training, so make you thoroughly understand the 'why', not just the 'how'.
I'm very curious about GUE, its not available in my area and I've never met a diver that has shared they were GUE. Short of being trained in the same manner and having a common gear configuration, I'm really curious as to what makes them better divers. They've paid a lot more money and done a lot more training dives, but once everyone hits the 50 tech dive mark I'd be very interested if there is a difference. My buoyancy on the first dive back from a break is not exceptional, that is not a mark against the agency or my instructor.
I think the biggest thing is a course where you know EXACTLY what’s expected. You must be able to maintain buoyancy with +/- this amount of deviation. You must be in horizontal trim, you must be able to master these kicks, and how they define “mastery”
Jim Wyatt does the same thing. You can’t swim with your hands ever. You can’t stir silt, ever, you can’t impact the ceiling or the floor, can’t frog kick, you’re not passing his cavern class. Bad attitude, bad buoyancy, bad habits with gear maintenance, your not passing.
it’s what he taught me and it’s what I’ve taught my students.
a few instructors scattered through the agencies are thorough like this, and all the GUE instructors I’ve seen.