I use Aqua Explorer's "Ultimate Travel Bands" and overall I like the design, It's very stable and durable. The exception would be the plastic cam buckles. I replaced mine with stainess steel after breaking a couple of the plastic ones gearing up for winter/ice dives.
I prefer independent doubles for extremely cold water diving as in the event you get a freeze flow, there is no absolute need to close the valve on the freeflowing reg. It's still beneficial and a good idea, but you are not going to vent all your gas if you don't. It makes me feel better if I am in some sort of restriction where closing a post could be problematic.
Gas management is often cited as a con. but in my opinion if you have problems rembering to look at your SPG now and then and are over loaded by the need to make 2 gas switches during the dive, you need to stick to very sallow single tank dives anyway.
In practice with 2400 psi tanks, it means breathing the first tank down to 1600 psi and then breathing the second tank down to 800 psi before making the switch back to the to first tank, which should get you back to the boat with 800 psi (1/3) in each tank. The math is even easier with 3000 psi tanks. This approach ensures that in the event you lose the contents of one tank, the contents of the other will be adequate to get you back to the surface or first deco gas switch.
Plus once you start diving it, it becomes very routine. The configuration also allows you to just breathe off one tank in a strictly recreational dive with what amounts to an enormous pony.
Personally, I have never had problems with trim issues with one full and one mostly empty tank. If you use the 1/3-2/3rd gas management approach the maximum weight differential between tanks is even less and should not pose any problems regardless of what wing you are using.
In the past, I used to use a long hose on the right tank and a short hose on the left tank and would clip whatever reg was not in use off on a right shoulder D-ring. (I have never been overly thrilled with bungeed octos.) Using a bolt snap attached to the reg with an o-ring around the base of the mouthpiece, makes it possible to access the reg without having to unclip it.
Lately, though I have departed from the herd and am using a M&J industries gas switching block with a single second stage. The block is mounted aft of the D-ring/light in the right waist strap and the hoses run down the backplate from each tank to the block. The hose feeding the second stage then routes up across the chest and around the neck to the reg. At 43" inches it is not exactly a long hose, but works well for gas sharing any place other than a cave. Since the majority of my deep diving is solo, it's a moot point. This setup also requires overpressure valves on each first stage as a safety measure.
Since most of my diving is sols, an Air 2 serves as my backup reg, but there's no reason a conventional short hose octo or bungeed octo could not be used.
This configuration has it's downsides, but the advantage is that the gas switches are a snap requiring only that the rotating knob on the block be rotated. Since the middle position is an "off" position, any unintentional movement of the switch will immediately get your attention so unintentionally breathing of the "wrong" tank is very unlikely as the switch is unlikley to be accidentally bumped over the center notch off position. With a switch block any task loading argument related to the mechanics of the gas switch itself, virtually evaporates.
