I'd imagine if you pointed out any service related problems may come straight back at them under warranty and it might be in their best interests to do a full service now,also giving you more confidence in their customer service and what to expect from them in the future etc.
Failing that walk away,if I'm reading your post correctly its priced at £3000?,if so that seems a tad on the 'too good to be true' side of things,has it been written off or something?,time for some searching questions methinks.
