Andy would be the best person to answer your questions Gill, but I may be able to fill in some of the details in my review below as I had a chance to set up the unit, tear it down and dive it. As far as diving the Pelagian, several of us had the opportunity to try the Pelagian in San Diego and we all liked it. My impressions of the unit are as follows:
Size of The Pelagian.
The unit is VERY light and VERY compact. I had a nice long dive with it and it trimmed out very nicely - I guess all those reports I read about its trim weren't exaggerated
. It is very streamlined and has a very narrow profile, although this depends on the tanks you decide to use.
Scrubber.
The Pelagian doesn't use a separate scrubber canister and is designed to be very compact. It holds about 2.8 kg of 4-8 mesh sorb and filling it is more involved than on the rEvo, but is not a difficult chore. Andy does have a longer scrubber that has an eight hour duration and still has the same diameter scrubber, which is small! The ability to use tanks up to 7.25" in diameter (Al80) makes using the longer duration canister an easy task.
Gill - adding a radial scrubber canister would result in reduced sorb capacity due to the small size of the scrubber tube. I'm not sure how much benefit you could get with a lower capacity radial scrubber than a standard Pelagian scrubber.
Needle Valve.
I had reservations about the needle valve and how well it would work, but after having dived it I found it easy to adjust the flow to match my metabolic rate. I thought it was actually easier to dive the Pelagian because once you set the flow you don't have to manually add as often. The fact that it doesn't have a blocked first stage means you can take this deep without modifications. For those who still fear the needle valve - just don't use it and add O2 as you would any mCCR - its no different. But adjusting it on the fly is very simple and effective.
Turning the needle valve completely down does not shut off the O2 flow, on the unit I tried, the flow at the lowest setting was about 0.1 lpm. Andy tests the flow with a flow meter to show this and also so you can know what your metabolic rate it. Its very easy to determine your metabolic rate at different work loads with this unit, just measure the flow coming out of the valve after setting it.
Counterlungs.
The front mounted counterlungs follow the shoulder straps of your harness (standard hogarthian routing) so they are to the side. I didn't find any issues with slinging an Al40, but access to the D-rings is diminished since the counterlungs are on top of the harness webbing. I'm not sure what it would be like slinging multiple bottles. I think side-mounting would be a good solution, but I did not try this. I did not find the counterlungs to be intrusive and the WOB was pretty good - no complaints here.
There are two things the Pelagian counterlungs can do that I can't on my rEvo. First is the ability to remove water from the loop and the second thing is that you can do a positive test on the rig, something I am not able to do with the rEvo.
Pelagian Display.
I am used to the HUD on the rEvo, but diving without one was not a problem. The Pelagian display is quite small and light and was easy to see and keep out of the way. I was able to keep setpoint easily, especially after reaching my depth and adjusting the needle valve. I also liked that the Pelagian display uses a reed switch to turn on the display. The cable is also very durable and the display can hang off it without much worry ... although I'm sure this would not be recommended ... its much tougher than the audio cables used in other display applications.
Head.
The head of the Pelagian is very compact. It holds three cells, which need to be modified in order to fit the compact head, and to allow for the Instant Cell Validation. I had reservations about this as well. But it is VERY simple to do and will tell you how well your cells are working very quickly. However - you will have to do some math to know what the PPO2 should be at the depth you test your cells at, but its standard math that every diver has gone through many multiple times in courses
ADV.
I was not able to reach the ADV to manually activate it. But in the scenarios we discussed there were multiple options for flushing the loop. The ADV is sensitive in certain positions so the user must be aware of this - but you can take advantage of this to do a quick power flush of your entire loop. The ADV worked well in standard positions, but was more sensitive in a head-up position and face-up position.
Position of Valves.
I like having the valves up top. I find them to be much easier to reach then behind my back, especially with my wing inflated. It also puts more weight on top, which is one of the reasons for the great trim.
CONCLUSION.
I had the opportunity to not only dive the Pelagian, but went through preliminary Pelagian training with Andy. This gave me a great opportunity to learn a lot about the unit and Andy's philosophies. I think the Pelagian is a very solid unit with great characteristics. I would need more dives on it before I can make any final conclusions, but I truly do believe it is a great tool for diving. I'm hoping to be able to dive it more in the near future to see how well it fits into the diving I do. One thing that I can conclude is that Andy was able to dispel the reservations I had on the Pelagian.
My only comparison is to the rEvo, which is a great rebreather. The Pelagian does have some things I like better, but the rEvo has things I like better than the Pelagian. So for now, the jury is out until more dives are done on the Pelagian.
Also, I have to say that it was great to have Andy here in San Diego. He met most of the gang down here, had a chance to watch a local band, drink local beer, and eat good ol' American food
Paul
(BTW - I have some pictures of Tyler modeling the Pelagian ... I'll post those later this week)