I'd love to add my two cents, but since I don't post often Ill let you all know I'm a PADI OWSI and TDI Trimix diver. I'm hoping to soon embark on my TDI and PSA instructor certs...
PADI's DSAT course, in my opinion, is sorely lacking and was clearly not designed or written by technical divers, but rather by PADI Lawyers and Educational Consultants. Not something I'd put my life on the line with. The way DSAT is presented by the materials, in a way that dumbs every concept down, avoids giving information that may be hard to grasp or handle, and creating an acronym that must be memorized for every simple procedure is not what technical diving is about. Other agencies (TDI, IANTD, PSA) provide you with a solid foundation in the actual physics, albeit basic. PADI gives us a nice little table, and does not tell us how the values on the table were formed and why the variables were chosen. PADI has us do a NOTOX gas switch, every time. I've NEVER done a NOTOX gas switch. I was taught to positively identify each second stage before I breathed it, much simpler imo. PADI has us STAGE DECO BOTTLES IN OPEN OCEAN ON THE GROUND!!!!!! This simply does not add up for me. I was trained to use the method that works best, has the fewest chances for failure, nd to THINK. PADI tells us how tech divers think, expecting that we will follow. I guess I was "groomed" to think instead of going for a manual to give me a procedure. PADI also has the most confusing omitted deco rules out there. I've never had to rely on Omitted Deco rules, but I know that hopping back to my last stop and adding the required times is much easier than deciding if I need to run plan a, plan 1a, plan 2c, or plan z. I also take a bit of offense when reading the PADI materials, instead of treating us like educated adults, and our instructors like the quality educators they are, they give us shortcuts and don't bother explaining the conceptual ideas behind these. When something does go wrong, having a solid understanding of diving (as opposed to being told what to do) will provide a better bag of tools and resources to meet the challenge.
Now, I am a US citizen, but I don't consider myself American (having only briefly lived in the US for university). It seems that Americans have become very rich and paranoid when it comes to diving. In my parts of the world, the only time a diver would use mix would be a deep penetration. I normally dive 60+ on air, many dive to the 70m+ range on air weekly. The narcosis seems to be half of the draw for some of my fellow divers. I admit, I dive mix when I am interested in seeing a certain landmark on a wreck (a big gun that 12 divers missed for three months, but the first mix diver clearly identified and photoed). I would never ask students to do the same, but knowing a bit about the actions of narcosis and CNS tox (as opposed to threatning language in a manual) make this something I'm willing to do, in a team or solo.
Some may think deep air divers are crazy. The pioneers didn't have mix. The founders of the tech agencies didn't have mix. I use mix as a tool, but I'm not willing to use mix because someone think that moving the "cns limit" back to 1.4 is good for legal reasons (let's be honest). I'd encourage all of you to seek out the information on CNS tox that your agencies don't publish. The time limits for exposures in sport diving up to 1.8, and (for emergencies) the numbers up to 3.0. I'm sure some of you already know that CNS tox only becomes an issue at 1.8, not 1.40000001 and not 1.6.
