Consider this, you are looking at a 2nd hand Golf
The first one has full main dealer stamps but is in generally poor condition. Its been owned by Shiela from down the road who couldnt give a monkeys about where or even how (kerbing wheels int he process) she parks, whether or not she eats a burger king in the car, whether or not to fling the door open onto a lampost etc etc. BUT yet she has always taken it back to where she bought it for a service (VW main dealer). And the car is sat forsale on the forcourt of such garage.
The second has
no main dealer stamps but yet FSH. This car has been owned by a general car lover. He/she has cleaned the car inside and out before your visit (private sale), kept all receipts, was careful never to open the door onto lamposts and watched where they parked to not kerb alloys etc etc.
I know I'd chose the 2nd option everytime. Lets be realistic, a service, when you get down to the nitty gritty, is just an oil change and oil filter. I have my Golf serviced by a JCT600 VW garage, it went in just last week. The mechanic who serviced the car is a pal of mine, cost me £80, used long-life VW oil, stamps the book with a JCT600 VW stamp and even puts a bottle of screen wash on the front seat when I collect it (which may or may not of been taken from the service desk

)
I will ask him about this "updating" that people are talking about. But in all honesty the service you get, even from expensive marque's dealers is often apauling. You are usually talking to the service desk woman/man who has NO IDEA WHATSOEVER about what has just been done to your car. All they have is it written down on a post-it note in amongst a big fat bill with your name on it.