[Padowan]

As a relative newbie myself, I can agree with your "anxiety" as to the number of failure modes, and the insideous nature of them. They will not make themselves obvious, you have to check for them continuously.

What I have found over the weeks that I've been (quite intensively) diving my unit is that my reliance ont he handsets, and the deathgrip on them that I had when I started so that I could look at them all the time, has dropped. I now "listen" to the unit, I hear and feel almost every injection, and based on (my limited) experience I have a good feel for how long and often it should inject. The handset checks (which I reckon I do every 2-3 minutes now) is a cross check. So being "in tune" with your unit I think is a great way of increasing your safety, as Hyperoxia and Hypoxia should be covered by this - no O2 injection you will be aware of 1) loop volume reduction if you run it minimal 2) not hearing injection. Hyperoxia you would notice 1) bouyancy change caused by excessive injection and 2) you'd hear the gas coming in all the time.

However being "in tune" with your unit will not help you with Hypercapnia - this really is a bit of a random element, but you can reduce the liklihood of this happening by keeping well within the time limits of the Lime and taking care when you pack the scrubber. If the scrubber monitor that they are putting on the Evo is as good as it could be, this IS a nice addition - but I fear that rather than adding safety, it will encourage people to push the scrubbers and ignore the time limitations - not sure what other perspectives people have on this. Lime's relatively cheap - just change it and be done with it, if you ask me.

Loop failure should be preventable by good equipment care and maintenance and a conservative and protective approach to penetration, where you might dislodge or tear a hose.

The BIG safety factor that you do get with a CCR is time. As DrMike wrote in a post a while back, when he got stuck in a deep wreck, he'd probably have been toast if on OC...

In the Red Sea recently I was down at 65m and felt very comfortable staying there, without the constant check, check, check of the bottom time and gas. This, I felt, led to a lower stress level on the dive, which in itself puts you in a better base level position if you do have to deal with a problem.

I take every RB dive seriously - you can't just sling it on and jump in, and because of this, even shallow lake bimbles for skill development have to have the same levels of equipment preparation as a 60m+ open water wreck dive - I think that unless you are the kind of person who can take this attitude, then complacency could potentially set in as the experience increases, and your "benchmark" for a non challenging dive increases - this is where it's likely to bite you I think..

My 2p.