Posted by Kendall Raine on January 10, 2001 at 10:50:52:
In Reply to: Which Scubapro reg combo is better , Mk20/G250 or G500 ? posted by dawhale on January 10, 2001 at 04:54:08:
Better is a tough one. Both the 250 and the 500 perform really well on the bench and in the ocean. In the more extreme environments, though, you just don't see the 500 used much. Lots of 250's, however. Also, in general, the small the reg, the worse the problem of exhaust bubbles in the face. If you have to work on it underwater, the bigger reg is simply easier to handle. Frankly, I like to old 250's over the new ones-I think they're built better and work better-though they're more vulnerable to engraving.
As for the Odin/Jetstream, the upstream functionality is really not an issue. It's been cited as a problem on this board, but that's dated thinking based on lack of understanding about how the Jetstream really works. If you have an HP seat failure, the reg is going to be very tough to breathe from, upstream or downstream. The Jetstream has an OPV at the base of the second from which HP gas escapes. Hence, you can breathe from this source. In the event of a free flow with either a Jetstream or a downstream, you're pretty much compelled to switch to the backup and either isolate the free flow or find another source of gas quickly. If the free flow is caused by a first stage problem, and you only have one first stage, the back-up will suffer the same problem. That's the reason first stage redundancy is important. I'm not endorsing the Odin/Jetstream, however. I've stopped using the Jetstream after seven years-though I still use the Odin-because of other design issues unrelated to this point. I just wanted to correct the upstream red herring. For more on Jetstreams, see some of Chris Grossman's posts on the functionality issues. He swears by them.