All in all, all mentioned binoviewers are very good, and there are no bad ones. Main differences are in prisms sizes and clear apertures, coatings, and mechanicall quailiy. You cant go wrong with any of them 
Wow, that's a bit of a let down... Come on, after all this careful consideration surely some binoviewers rise to the top? You must at least have some opinion... which binoviewer(s) do you like best for your own viewing?

Dave
PS. Forgive me if I missed it... I scanned through all the photos looking for some kind of verdict...
Look for ones using Fluorite Glass. They absorb less light and cool faster.
LOL.. Only kidding.
I have owned seven different binoviewers of all types, and I found that there was little I could see in one that could not be seen in another. Differences were subtle.
To me, more important is that the Bioviewer should be looked at as a system.
The big binoviewers with power switches offer versitility that stand alone units don't offer. This allows them to generally work with all three telescope types (refractors, Cats, and refectors) and while people think of them as being expensive, by the time you buy another device and pay money to have it supercarged, then add adapters and additional eyepieces, in the end, you will spend as much on a la carte systems.
The Maxbright is unique because when used with a T2 standard prism diagonal it will reach focus with many refractors. You can add adapters to the WO to do this, but once again, if you need to add something like a 1.25x GPC, you really won't save money by going to the WO.
My advice to people it to not turn this into the Eyepeice forum where the focus is on tiny differences in performance that are subtle and hard to see, and instead focus on the fact that the binoviewer is a system purchase for most people because to get the best performance from many scopes (lowest power, no vignetting, etc) the system becomes a critical factor.
My own opinion is that the variable power systems are the absolute best solution for most people that have multiple scopes because they cost about the same, but offer better flexibility and not changing eyepieces makes the much more efficient for observing.
The Mark V rules when it comes to people that want to go a la carte because once again, the system is the best on the market (not the binoviewer, but the T2 system itself), and for the Mark V, if you are going to own binoviewer where you have to change eyepieces a lot, nothing makes it easier than the Mark V.
To bad they don't come with Fluorite prisms though. Everybody knows that it can't be perfect unless it has Fluorite glass.
Sorry. Could not resist. Just that I would hate to see this forum go the route of the eyepeice and refractor forum by suggesting you have to have Fluorite Mono-centric binoviewers to get great views. All of them can give extremely satisfying views and not everyone can afford a high end unit.