I know it isn't what you wanted to hear, but it's still to a bit the instructor.
My experience has been that GUE instructors have the highest expectations and are the most critical of details. There are times when I'm of two minds whether that's optimal.
I like the UTD divisions of training, breaking things up into smaller, more manageable chunks. I also think Andrew has a great, inclusive vision, and wants to keep the agency focused on the fact that people do this for FUN -- even while they are training divers to a high level of skill. I think the cave branch of the agency needs some work, and if cave is what you are primarily interested in, I think GUE has it hands down.
I think there are some TDI instructors who are probably world-class -- I'd take a class from Steve Lewis in a heartbeat. But my TDI Cave class simply wasn't in the same league as either the GUE classes I've taken, or the NACD class I just finished.
Sorry for the hijack but I'm a little confused by your post.
If your interested in caves & "GUE gas it hands down," why have you done an NACD course?