well, apparently i've created a monster, although i did get a pm from a certain person in my area that corrected me that SDI is not the technical side. Basically according to his snide little pm i'm an idiot, but that's another story.
Anyway, the one thing i do like about the couple of TDI manuals that i've looked through, they are pretty well spelled out in "dumb people" terms, which is good for me.
I think everybody's opinion on agencies seems to be biased depending on what agency there trained by.
Just my opinion.
It's true though, that SDI is their NDL side, which evolved as an add-on to their tech side. Sort of the opposite of PADI's tech side, which evolved from their NDL side.
When you therefore speak of tech, it is about IANTD, NACD, TDI, NAUI Tech, GUE, AG-DIR, etc. I do not know if BSAC (Europe) also offers tech. And, oh yah, PADI has tech now too.
If you even have a tech choice in your area, then you are quite lucky. Often, anyplace you go has either none or only one. I know of only one OKLA tech diver, and he is IANTD. I think he lives near OKC and dives in Latonka Lake or Elmer Thomas down in the Oichita Mountains. Those are really deep, clear lakes. The US Army at Ft Sill uses them to train their Green Berets on scuba, last I heard.
To answer your original question, I would suggest looking around and finding out what is available. Then if you even have a choice of more than one in your area, meet the tech instructor(s). This person's personality is going to be the most important thing in your life for the next year as you put your life into his/her hands. Ask to meet some of her/his former graduates.
See if he/she maintains a good group of trained tech divers that you can go diving with after you graduate from the program. I will concede (although I am not DIR) that this is the greatest strength of the various DIR programs (GUE-DIR or AG-DIR or NAUI-DIR). They get their people out and they go diving.
If you did well in college physics, chem, or math then you should have no problems with the tech curriculum. The issue is simply one of determining your depths, computing your pressures, selecting your gasses, programming your deco, fine tuning your diving skills, developing protocols and procedures, and then going diving!!!
Although I am not NAUI TECH, I would have to say they probably have the best program overall. However they may or may not be in your area. They are strong in Florida, in Southern Calif, and here and there across the USA. However, having said that, I have good tech friends who have recoilled from NAUI TECH's inflexible methods.
If you like things to be structured for you, then any of the DIR programs (GUE or A/G or NAUI TECH) would be better for you.
If you revolt away from any type of imposed requirements, and perfer freedom, then IANTD or TDI is probably your best bet.
It all depends on your personality and what makes you most comfortable in the water. It is too easy for someone else to tell you which they think is the best tech agency. But you need to figure that out for yourself.
