I've been selling off a few old lenses in preparation for an eventual move to a Canon 5D2... my dilemma is which ultra wide angle lens would replace my current 10-22 lens...?

I've been heading towards a Canon 16-35mm II, though by all accounts its barely better than a 17-40mm on a full frame, at twice the cost, with significant barrel distortion and CA.

An opportunity has arisen to buy a used Canon 14mm II at a vaguely half-reasonable price (still more than a new 16-35mm...).

I'm tempted, but was wondering if anyone here has tried and tested the 14mm? Particularly relative to the 16-35mm? I'll be shooting mostly landscapes and architectural shots with the lens.

I do love insanely wide lenses, which would suggest the 14mm is the right lens... but then I wonder if its too big a gap between the 14mm and my next widest lens, the 24-105mm? Probably OK.

Any thoughts appreciated...