mointampa:
... whether to get a Zeagle Ranger or Posiedon Techlift ...
Between the two I'd get the Ranger. High quality, plenty of size and acessory options, very good weight integration and excellent customer service.
I neither know the Techlift nor Poseidon's customer service, so I can't make any statements in that regard.
If you have your mind set on a 'normal' BC, you might also have a look at DiveRite's Transpak II. A lot like the Ranger, even more versatile, and the same excellent customer service. It is also a bit less bulky, one of the few nitpicks I have about the Ranger. What both, and probably all three share is a lack of stability (a single tank will move about left and right).
That is one reason why I prefer a bp/w. The other is bulk, they have much less of that. So I agree with johnnythan on that:
johnnythan:
... Check out a backplate with wing ... but trust me when I say they're the bee's knees ... The difference they make in weighting, buoyancy control, trim, comfort, and stability are simply amazing.
In my case I chose an DiveRite aluminum bp (I have a very negatively bouyant steel tank, with an alu tank I prefer a steel shingle) with Oxycheq's 45# wing and a continious harness. The circular single tank bladder is more convinient to dive than the horshoe shaped Zeagle. Weights less than the Ranger, packs smaller than the Ranger, is much more stable than the Ranger. You can add just about any acessory pretty much anywhere you want.
As I liked Zeagles Ripcord weight system I picked the DUI weight harness. It's operation is close to that of the Zeagle, with the advantage of quick-releasing one side at a time, and being separate from the harness (can be mounted on the harness, too). The latter makes it easier to don, doff and move around the bcd with tank as you already comfortably wearing the weights.