Bring on the 14-24 2.8L please...I envy my friends Nikon 800/14-25 setup, amazing lens body combo. It's about time Canon at least puts up some what of a fight at this focal point.
Interestingly, with your friends setup, it's the lens which is the limiting factor there, not the camera. Very few lenses can match the IQ demands of a 35+ mp sensor.
A TS-e 17 will out resolve nearly every other wide lens and with its movements, one can cover an effective 12.5mm focal length if you are prepared to tripod, shift and stitch. It's certainly a nice technique for great panos.
The Nikkor 14-24 is good at shooting lens charts but not so useful shooting landscapes imho compared to a 16-35IIL. The bulbous front element makes filter use difficult (like the TS-e 17L) and costly. The resolution wide open on the 14-24 is extraordinary...but stopped down (for DOF) there is little real world difference between it and the 16-35IIL. The extra 2mm at the wide end can usually be nixed by moving a little further back and it's a small benefit vs the problems fitting a polariser and ND filters are compared to the ease of a 16-35IIL.
In my opinion both the TS-e 17L and 16-35IIL are better landscape optics than the Nikkor 14-24....unless you liek to shoot brick walls or lens charts that is ;-D