Thanks. Have you tried the Samyang? It's one of the few Samyangs I haven't owned/used. I'd be interested in hearing a first-hand experience! If the Samyang has a worse IQ though, it's not worth it, you get what you pay for, I rather pay more. Who ever heard of a cheap TS lens! I'll read the review you linked now.
Ps. is the 17mm L or not? I though it wasn't an L lens but amazon lists it as an L lens! Which is it?
No, I have not used it. According to reviews it seems to be a less-expensive alternative to the Canon if you don't plan to shoot with apertures wider than f/8, if you don't expect the same image quality, but you need the tilt-shift. At $1000 it is not exactly cheap.
Here are two more articles by Roger: