I have recently completed tec 40 and 45. I believe if you have the right instructor it IS the equivalent of AN/DP for TDI. I have the AN/DP manual and required skills/knowledge to qualify and I did all those. If you have a good padi tec deep instructor who has actual deco dive experience it was awesome. I got my butt kicked to china and back twice! and came out the other end a much better diver (It did take me nearly 9 month for both tec 40/45, even with 500+ dives as a rec. instructor, but I have a feeling I got an extra butt kicking beca iuse I am a rec instructor, it was never pass or fail for me, I had to practice and improve before I was able to final certification dives) What I have learned in the last year has made me such a better diver, and I was already humble and I still ate pie. p.s. done in doubles from tec 40 and in 45F water, added dryglove gloves to suit after first "intro dive" on doubles)
As far as respectablilty....I have thought alot about this....Padi tec is a dirty word....as a padi instructor I am acutely aware of this...I can either buy into the common thought that I SUCK or do my very damnest to be the very best diver I can be regardless of the card I carry. I have seen experienced divers & instructors in the water who started diving & teaching around the same time as me, and I know the various agencies of cards they carry, that doesn't matter to me as to what the card du jour is. They just seem to have the attitude of continuing to strive to be better, that IS respectable.