It's complicated.
Let's start with the fact that I don't have any plans to do any deco diving. The reasons have much to do with a lack (locally) of technical dive teams who are looking for new members and an absence (again locally) of interesting dive sites in the relatively narrow depth range where AN/DP is helpful without helium.
The next problem is that most tech shops here are PADI; there are only a couple of SDI/TDI shops and while they do offer AN/DP they have limited slots and it is logistically very difficult to take the class. The PADI tech progression requires a much larger investment of time and money to reach a level of certification where you can buy 100% O2.
To take AN/DP locally requires a drysuit, which I don't have, and requires travel to one of a handful of deep sites all around 200 miles away. So there are a bunch of barriers.
I think, if I were to take AN/DP or similar training, I would prefer to fly somewhere else for a week and do it there, with an instructor who really likes to teach it, and on dive sites that are rewarding in their own right rather than just a 150' deep platform. And I don't have the time or money to do that this year.
I did. It might be a bit of an extreme solution to your problem but with the right instructor, AN as a stand alone class is an excellent course with no need to go deep.@2airishuman why not just take AN as a course? I think @uncfnp only took AN due to a medical concern that I can't remember off the top of my head. It's not a common request, but if someone came to me with that request, I'd certainly teach it without doing DP.