I realize that the original poster said his instructor was a GUE instructor and a IANTD instructor but I don't think this is a decision that can be made on the basis of economy or convenience. The differences between the IANTD (or TDI) courses and the GUE courses go beyond the number of courses and prerequisites. They differ in basic philosophy.
If you want to learn to do technical dives DIR, the best way would be to train with GUE. I have taken technical classes (my advanced trimix, in fact) from a honest to goodness DIR diver. In this case I'm defining "DIR diver" as one who is a member of one or more exploration groups that oporater in a strict DIR fassion. Still the requirements of the agency the instructor is teaching through must be met. Even if it doesn't effect how the actual dives are done, it will certainly effect what written material is covered, how and the nature of the written tests.
In the case of IANTD one of the major differences is the equipment philosophy. IANTD attempts to teach a student how to anylize an equipment configuration, presents several configurations used by well known divers and, in theory, lets the student choose their own. This is required material in the IANTD course. As you know, no such choices exist with GUE. I don't mean for this to be a statement as to which I think is better. I have all the respect in the world for both Tom Mount and JJ but there are many things that the two do not see eye to eye on and it shows in the design of the courses of their respective agencies.
Some other major differences might be found in gas selection, decompression and certainly in the view on rebreathers. For instance, most if not all IANTD courses can be taught using rebreathers and that's not going to happen with GUE. IANTD permits instructors to choose decompression gasses like 80% as apposed to O2...another thing that isn't going to happen in a GUE class. GUE, as far as I know sticks to standard gasses pretty strictly and IANTD doesn't (or at least it's not required).
While I haven't taken a GUE class I would also expect there are some differences in actual in-water skills that are required also. Again these will reflect the differences in philosophy between the two agencies.
As I see it, if you're concerned with more than ending up with a card that says you can dive trimix, there's plenty to think about.
