Before they started using rebreathers, Poseidon regulators were the choice of Navy SEALS. They are still very popular with deep wreck divers because they are so reliable.t two of us have pointed out. That's why there are only one or two companies that mIndustry wide they are considered a bad idea and for very good reasons that at leasake them. I've dived cattle boats as a DM from 2007-2012 and very few divers are using them or Poseidon regs for that matter. It's not common place and they are a liability. Best of luck to your dive buddy.
Mine was a hand me down and is older than me. I have never had a single problem with it.
That is the only drawback. If you need service, you have to find an authorized Poseidon service center. My local dive shop won't touch mine, I have to take it to Orlando. There is also a very good Poseidon repair tech in Key Largo. He told me the Poseidon design is so good that it hasn't changed since they invented it.The Poseidon regulators are good - just finding a knowledgeable tech can be a problem. I used to service them, but lost my certification a long time ago.