@Will Megginson ...
The first thing about technical diving is it's not "recreational" diving per-se. It's outside of recreational diving in that it requires different equipment configurations and different / better skills.
DiveMasters are generally not technical divers. This is especially the case for those who're completely ensconsed within the PADI/recreational diving system and who are not trained in the skills of technical diving.
Not all DiveMasters are cut from the same cloth; there's plenty who are technical divers. Just be aware that there's little technical knowledge in the recreational community.
...
Regarding books; I'd suggest getting one and reading that. All the others are great for background reading; you need to have one to get off the ground. It's also cheaper to get only one book.
Technical Diving an introduction - Mark Powell