Anyone have a R107 280SL?

[tog]

I'm trying to persuade my girlfriend that what she needs to replace her old-shape Megane convertible is a 1980's 280SL. She's almost convinced, and I think we might be going to look at a couple next week, but is she right to be hesitant? Are they as reliable as they're made out to be? (Anything would be more reliable than the Renault though...) She's mechanically sympathetic, so knows when things aren't right, but doesn't know the first thing about actually mending cars or how they work. If we got one, roughly how much should one allow for servicing / routine maintenance for a mileage of around 10k-12k a year? Will assuming minimal or no depreciation roughly offset the higher running costs of the Merc? And what sort of mpg will the 280 give, or is the 300SL any thirstier?

Anything else I should be aware of?