How would you really feel if you found out your tech instructor had been teaching for 1 month?
I clipped your post because I agree with a most of what you said, so I'll just respond to this part of it.
It's been my experience that
some instructors have been teaching for 30 years, and teach old, antiquated information that doesn't take full advantage of technological and procedural advances in diving. You've got to balance experience with reluctance to change.
Now, furthermore, my judgment of an instructor is based on what he/she teaches TODAY. Because a person has no experience teaching, wouldn't cause me to not take a class with them. There's benefits IMO to getting a fresh instructor who's motivated and excited to make the best divers he/she possibly can. Also these divers stand a good chance at being more active in diving, which might allow them to see more new divers on a weekly basis, so they're reminded of what to look out for. There's also benefits to experienced instructors who have been teaching for years though, and I'm not denying that.
Some great instructors lose interest in teaching 10 years into it, and begin to just do it for the money. Asking a student who took the class 10 years ago to give an opinion isn't something I'd do. I know I've seen friends in every field that are excited about a new job and bust their butt for a year or two, and then slowly become lazy and put less effort into it.
All in all, I think the best thing a diver can do is spread his training around to several people, and look for the best instructors based off of reviews of recent students.