I'm in the same position.....
I've just bought a GT TDi 140 for the wife and changing the bland rear end is high up on the things to do list but as you mentioned, I'm a little wary about the quality and fit.......
The pictures they have added where fitted and painted look great but I wonder how close their copies are to the originals......
If you buy one you can let me know!
I'll need to bite the bullet soon and decide on what to do.