Combined Jackets
I origionally bought the Jacket, mostly because that was what I was used to using. As I dive almost exclusively with a drysuit I very rarely use my BCD underwater. I added wings because I started to dive with a twinset, and needed a little bit more lift than the jacket provided. I have (with a single tank) used just the wings, and just the jacket for buoyancy at the surface.
Just Jacket - floats me nicely head up, no problems.
Just the wings - floats me face down, unless I actively try and float on my back, getting the weight of the tank under the wings.
When I have a twinset on, I find that when I surface I fill the BCD first, and after that will start putting air in the wings. This tends to not put me face down, probably due to the larger ammount of weight on my back.
After using my combined jacket I don't think I would use wings by themselves, I think this is where the back inflation jackets come into their own. They aren't wings, they are a jacket with quite a large part of their buoyancy behind you, but they retain some of the buoyancy infront of you for head up at the surface.
I can't remember, as I have had little experience of the Dacor RIG (they don't seem that popular in europe) but I think that the Dacor RIG is one of these back aircell Jackets isn't it? - If it is, then it is probably quite a nice jacket.
Jon T