I'm looking to move on to my AOW cert and there is a plethora available in the DFW area. The shop I originally got certified with was bought by another so I was shopping around and checking prices and noticed how many were available. SDI, SSI, Naui and Padi just from my limited time looking. My OW cert is from Naui but I've read that there are advantages to learning from different agencies. I guess I'm just hoping to get some feed back on differences, advantages/disadvantages and stuff like that. Oh, and is it normal for the SDI course to be double the others? Thanks in advance.