I was only interested in the 16-35 to use on a FF camera. If the IQ was significantly better than the 10-22 I would wait, and in time, eventually get a FF camera and the 16-35mm.
The IQ from the 16-35mm on my 5DII is better than that of the 10-22mm on my 7D in terms of sharpness, color, and contrast. AF performance is better as well, due to the f/2.8 aperture. However, at 16mm there's more barrel distortion making it less effective for architectural shooting than the 10-22mm (although the latter still has some
distortion - when I want no distortion, I use a TS-E lens). Also, if you want UWA on 1.6x, the 10-22mm is the only option from Canon.
The build of the 15-85 is great, probably as good as a plastic L series lens, though there are very few plastic L lenses.
Going to disagree on that one, although I did make that comment about the 17-55mm on another forum, once upon a time. The optical quality of the good EF-S lenses (17-55, 15-85, 10-22) is on par with many L-series lenses, but the build is not. In addition to things like weather-sealing, L-lens zoom rings and focus rings move more smoothly, with a zoom there's not the same 'hollow clunk' when you hit the end of the zoom range, etc.
Incidentally, you're wrong about L lenses with plastic barrels - almost every current black L lens has a plastic barrel! The 16-35mm f/2.8L II, 17-40mm f/4L, 24-70mm f/2.8L, 24-105mm f/4L IS, 135mm f/2L, the 180mm f/3.5L Macro, TS-E 24mm f/3.5L II, and I could go on and on...all plastic barrels. But, the quality and thickness of the plastic, the underlying metal frame, and the overall sturdier feel of those lenses make it hard to tell that the barrels are plastic.