I'm thinking you should check and see what regs your LDS carries and services.

The dry throat is caused by the very dry gas you are breathing from scuba tanks. Not much you can do about that except switch to a CCR, or (much cheaper) carry a small bottle of water with the pull out top.

My preference is for Poseidon Odins because they are unidirectional and work well for just about everything, but I understand that parts are becoming a problem due to a corporate re-org.