I think it all boils down to one word - trust.
If you trust the main dealer's expertise to be worth paying the extra for - then do it.
If, on the other hand, your local Renault dealer tries to sell you either a Megane or an Espace (when you want a Vel Satis) - one too small, the other has too many seats, and says that only 15 were ever sold in the UK...(out by a factor of 100)
Then you go to a tried and trusted independent. As I do.
I would rather entrust my car to a knowledgeable, passionate independent (who I can deal directly with), than an organisation where you need to double check that requested work has been carried out.
A bit cynical, but I've had some poor experiences to draw my conclusions on.
Paul
