There's three reasons why I'd want to travel to dive with specific other instructors:
1) Dive Skills. At my level, this is typically orientated towards tech diving. I'd rather defer training for a year or more, than simply book with the nearest qualified instructor. My first tech instructor was Mark Powell... that kinda set a 'high bar' for subsequent training. Bruce Konefe ran my latest course - teaching technical wreck to a guy (me) who'd be doing technical wreck diving regularly for the last 8 years. The course was invaluable and I learned a lot - which speaks volumes. In my mind, that's the mark of a truly expert instructor - someone who can add value, even when the recipient already has a high level of knowledge and skills specific to the subject. Nowadays, I don't really care about the course - it's the person that I want to dive with... I'd take a technical wreck course again, if that could be a vehicle to get in the water with a different world-class diver in that field.
Sidemount is my most recent baby... and I'm in love with it. Bruce qualified me in that also, and it was very comprehensive. I'd still want to dive with other experts, just to see the different approaches and viewpoints. I love the knowledge and I value all those priceless little 'tidbits' you can get from training with a different person, who really knows their stuff.
Doppler and Dive-aholic are here on the forum - and I'd want to train with them. There's a myriad of other world-class instructors/divers, not on/frequently seen here on Scubaboard, that I'd travel to train/mentor with - Chatterton, Gentile, etc
2) Instructor Skills. Teaching is an art. I want to be the best instructor that I can be. I've done courses with other instructors before, simply to learn more about their teaching methods and approaches. When I initially qualified as a tech instructor, I spent the first few years simply deferring my students to other tech instructors - so that I could assist them and learn myself. I felt that the value I gained from doing that, as a tech diver and instructor, was worth far more than the cash I'd earn from teaching the students myself. It was an excellent foundation - and I'm now confident that I can offer real value in the courses I teach. I won't teach anything nowadays, unless I am confident I can offer exceptional value on the subject (and yes, that means I only use about 25% of the instructor level qualification I possess).
NWGratefulDiver, Jim Lapenta, Rick Murchison, TS&M and Quero would be on this list. Truly excellent instructors that I'd love to see operate.
TS&M and Quero are on the list because they're two of the most empathetic, sensitive and diplomatic instructors I've seen on the forum - and those are qualities that I'd definitely like to develop in my skill-base/approach. A near life-time in the military environment didn't equip me particularly well for sensitivity - although it's something I've been working on for many years. LOL
3) Fun. There's nothing better than getting wet with a like-minded, equally competent, diver. I'd travel...and go to quite some lengths... just to make opportunity to dive with someone who interested me. Whether a course or not, an instructor or not... some people are always enlightening to dive with... and if that challenges existing preconceptions or supplements new perspectives into the whole, then it's a very positive experience.
