I dive an RX-650 as my singles rig. The rig has performed very well for me in all situations and positions in the water. Jack said it best when he stated that this reg cannot be beat for the money. I have had the chance to compare this reg to other top quality (read higher priced and better marketed) regs that are on the market today. I am very impressed by the Sea Elite regulator. I normally dive Atomic M1's and to say that the RX650 preforms better than the Atomics would be inaccuarate, but the RX650 is one of the best breathing Regs I have ever encountered. If I had choice between the $500 Z2x and a RX650 that half the price of the Atomic, I would choose the Sea Elite as long as price was a factor. I feel that the second stage of the RX-650 has better case geometry and a lower exhalation effort than the Atomic, but the Automatic Flow Control feature of the Atomic is simply awesome. When each are tuned properly, I doubt that anyone could truly discern a difference between the Atomic and Sea Elite regs in overall performance.