I think DaveB touched on the point with the rears. I bought a HEL rear line kit for my Skoda Octavia VRS (so same idea as the MkV) to go with the S3 calipers that I was fitting. However, I noticed that HEL provided a perfectly circular end-piece to the lines (i.e. the ends at the bottom of the photo) whereas the hole that they were to pop through on the silver bracket on the caliper were 'D-shaped with a little groove on the flat part of the 'D'. I therefore ordered some S3 rear lines which were exactly the same as I suspected. However, as DaveB mentioned, I just took a largish circular file and made the 'D' into an 'O' and they popped through and clipped in place. Not really a biggy but a bit of a hassle when, as mentioned, the braided rear lines don't really do a whole lot.
So spare S3 rear lines in my garage if anyone interested.