Typically, I wear my Cannondale piece over a light synthetic T-shirt. I find it remarkably warm and versatile, especially when out on weeknight winter rides with my local cycling club. Cycling is a pretty tough test for an insulating or windproof piece, as you can be sweating up a storm when going uphill, then get badly chilled when descending the same hill. But I find that the Powershield piece keeps my torso temperature steady for the entire ride. It also keeps me dry in light rain.
For hiking, backpacking, that sort of thing, the REI item could be taken in place of a fleece jacket. A very light rain shell (Powershield is water resistant, but not waterproof) could replace a heavier Gore-Tex-type jacket. The One Jacket would be what you wear most of the time, and when it starts raining hard you pull on the rain shell. It's true that it doesn't have a hood; I prefer hats, anyway, so that doesn't trouble me. As for the low-riding pockets, you're probably right that a hip belt would block get in the way.
So that's the Gear Guy lowdown. Good luck!