I did one try-dive on an O2ptima before I bought my first rEvo. I now have about 100 hours on rEvos. So, this is one more reply from someone that is pretty inexperienced with CCRs. Take it for what it's worth.
When I did the try-dive on the O2ptima, I did not like:
- the front (over the shoulder?) counter lungs. Specifically, I did not like feeling like I had blinders on, blocking my peripheral vision.
- the instructor put 12# of lead on the very top of the unit and I still had to scull my fins constantly to keep my feet up, in a semblance of horizontal trim.
Despite that, I liked the experience of silence in the water enough that I knew I wanted to get a CCR. I just knew (at that time, anyway) that I did not want an O2ptima. I still don't want an O2ptima, but who knows what the future holds....?
I bought a used rEvo III Mini and dived that for over a year. Then I found a used rEvo III Micro for a good deal, bought that, and sold the Mini to a friend. Between the two, I have a bit over 2 years and 100 hours on them.
@Wibble made a point about rEvo flooding. He said its weakness is flood resistance. I want to correct that. It is very flood resistant. It is not flood tolerant. In other words, the design of the rEvo is such that it seems (in my VERY inexperienced view) to be very resistant to flooding. There are only 2 hoses in the breathing loop. With the standard DSV, there are only 2 nuts to put on and tighten. Other units typically have 4 hoses, T pieces, and, so, many more places where an O-ring could leak, for example. Some other units also have exposed counter lungs which, I *think*, are more likely to get a cut or rip in them during a dive than the rEvo counterlungs. It seems to me that the rEvo is probably one of, if not the most, flood RESISTANT units on the market.
What it is not is flood TOLERANT. Meaning, once you flood it, you are not getting the water out during the dive. Everyone talks about the rEvo like it's a 100% negative to the rEvo on anything related to flooding. But, to me, it seems like it's more of a pros and cons situation. It's less likely to flood (a pro), but you can't get the water out if it does (a con). Only you can decide which way to go on that.
I flooded my Micro once. Totally my fault during assembly and checks. It was a slow flood and I completed a 90 minute dive, on the loop the whole time. I didn't realize it was flooding. My only clue, until close to the end, was that it seemed a little harder to breathe than normal. But, even then, I wasn't sure. Towards the end, I rolled onto my side and the salt water got into the sensor tray and 3 of the sensors went whacky. But, the 2 that were only connected to my NERD continued to function perfectly and they, with the NERD and me flying the O2 manually, are what got me out safely.
I don't know any more about the O2ptima than what I already said, but I have several friends diving Megs. I was surprised to learn recently how much weight they have to add to those units. I have been told anywhere from 14 - 18 pounds (diving dry) or something like that. The most weight I have ever added to my rEvo was for cold salt water diving and I had 8#. Most of the time, I don't need to add any weight. At the same time, I have dived it in Utila for a week in just board shorts and a rash guard and it was absolutely NOT so negatively buoyant that it caused me any issues whatsoever. My friends with Megs have told me that they can definitely feel all that extra lead they are pushing around in the water.
I do have my rEvo rigged with a single piece of 2" webbing, Hogarthian style, for the harness. And I have a Nomad XT wing, in place of the standard rEvo wing. I think the shape of the Nomad wing really contributes to keeping the tail up, accounting for why I have never needed to use trim weights on my rEvos and I still have no trouble staying in good trim.
Things I especially like about my rEvo Micro:
- it is so light and compact, I think it is a great choice for flying with. I can fit my Micro in a regular hardside suitcase, with padding, and still have it be under 50#. I have flown with my Mini that way (breathing loop and computers packed separately, to keep it under 50#), and shipped the Mini and the Micro back and forth across the country for service that way. Never had ANYTHING happen to any of them.
- I have the rEvo BOV and it seems to be a good, solid BOV
- the dual scrubber setup - VERY unlikely to have a breakthrough due to channeling, plus using sorb more efficiently
- rMS - it was apparently very fragile when they first introduced rMS, but from what I can tell, they have updated the design over the years and it seems to be quite solid now. And it also really helps use sorb more efficiently. I get about double the dive time out of my sorb that I would with no rMS and, thus, following the factory specs for dumping the sorb.
- the CMF gives me a lot of extra margin for error in terms of time that I have to notice if the solenoid fails. It also substantially reduces battery consumption by the solenoid, since it doesn't have to fire that often.
- the counterlungs on the rEvo Micro are just about the PERFECT size for me and my lungs. I.e. they are only barely more volume than what is Optimal Counterlung Volume for me. I have minimal impact from errors in letting my loop get too full.
- 5 cells means I run the controller and a NERD2 monitor and I have 2 completely independent systems for monitoring my ppO2 and for calculating my deco. My controller and the solenoid could all totally die and my NERD would still be showing me 3 cells (I use a splitter with isolators on 1 cell, so controller and monitor each get readings from 3) and telling me my safe ascent plan.
