As a landscape shooter I use both tilt and shift pretty regularly. If your foreground is at all close, 24mm can still benefit from tilt to increase apparent DOF. Usually just 0.5-1 degree tilt is enough to make the the difference between infinity being really sharp as opposed to just "close enough".
I can see how tilt would be less needed for architecture; but if you ever decide you want to use it, it's likely you'll want it on the the same axis as shift. You'll probably be using rise/fall for perspective and tilt for near/far DOF. I suppose it's possible you'd want swing to match DOF to a horizontally receding surface, but I can't say I've ever needed that. So to me it makes more sense to have them together rather than opposing.
The modification is pretty easy to do yourself, there are instructions floating around on the internet including pictures. It basically comes down to removing 4 screws and rotating the back part of the lens mount. So I guess if you use the lens for a while in its default configuration you can always decide to change it later.
