When I decided to get a Golf GTi, I had decided I wanted a MK7.5 TCR and did a lot of research on these whilst looking around. Like you I found that the MK8 CS was very well priced in comparison to the TCR's, around the same and sometimes less. I went and looked at both, really liked the TCR, but much preferred the new tech and modern elements of the MK8 and ended up getting the CS. I do understand concerns over warranty and how new these are, you can always get an extended warranty or an all-in package from VW for peace of mind. (With both really). If you already have the MK7.5, then the next logical step is the MK8 and it'll feel like you've changed rather than getting the same again. Go take one for a spin, it'll probably sell it or even not! (In which case try something else or stick with your PP).