You could also get a Zork, or a mirex, or a cambo x2
Hi Will,
I've definitely thought about it too. Sure it would work but the canon 24mm is not such a great lens. The tse 90 is a very good lens, but still no match for other glass. That being said there are several options that will allow you to use better glass.
I have the zoerk MFS system which I have used extensively with the 1Ds and 5D as well as my leica r8/dmr combination. It's much less expensive than the horseman or cambo x2 setups and you can use quite a variety of glass with it. I mostly use a 80mm Rodagon APO enlarger lens, which cost me less than $200 used and is every bit as sharp as my leica 100 APO macro but has a medium format image circle. I don't believe you can get to wide with the MFS but you can get 30 degrees tilt (or way more than enough).
Another option that is very cheap (but I have no personal experience) is the mirex T/S adapter that will allow you to use either hasselblad or mamiya lenses on your 1DS with 11deg tilt and 11mm shift. It's a nice looking solution for only about 370 euro and as you may know you can find mamiya lenses quite cheap. A real plus if you also shoot MF and use one of those two systems.
I find that with both the zoerk and the canon tse lenses (I have both the 90mm and the 24mm) the viewfinder is good enough, but I think live view would be very helpful for macro and a lot easier than a view camera since the image would not be reversed or inverted.
If you are doing very precise work, then perhaps the cambo x2 would be better but its a heck of a lot more bulky than the zoerk or mirex adapters. I shoot handheld all the time with my zoerk.
Hope this is helpful.
Eric