You should buy the colour you want but play them off against each other.
I wasn't sure on the colour of mine as it doesn't seem to photograph anything like it actually is, so I put a deposit on it on the condition I could get the deposit back if I didn't like when I got there.
Everyone who saw the photo commented on not really liking the colour.
When I saw it I loved it (still do) and everyone who didn't like it in the photos loved it in the flesh !
Have you considered a facelift Cupra instead? - there's very little difference and they're a whole load cheaper than an R (shameless plug as mines now up for sale)