Well I had the opposite experience there when i was buying a 550. I was looking at a black car they had, wouldn't haggle on price at all even though car had been in showrrom for ages, they seemed a little snooty. But most of all car weas originally Grigio Titanio and they did not even bother mentioning it.
I found out from other sources (think here) and only then did they decide to mention it.
But £6k is £6k, so it wouldn't stop me going back.
Would mainly be trips from West London to Ascot, so motorways and A roads, but not worried by clutch, I do too many lunges/ squats to keep fit as it is to keep my 550 clutch seeming light as a feather!
How long does the clutches last on the 512? Are they fairly hard wearing?
My biggest worry would be parking it outside, from what I have heard (opinions welcome) it would crumble fairly quickly.