I had the autoglym lifeshine on my black GTI and I'm glad I did. My mate bought a TT just before me and he struggles to get insect remains off it even when using insect removing products, i just wash mine with the autoglym shampoo they give you as part of the lifeshine pack. Washing my car is so easy and, as it's been said before, it comes up like brand new.
I was in two minds whether to have it done like you but I thought whats another £299 out of the £21k i'd just spent. I'd have it done again and my mate wishes he had too.