I have a 1968 Coupe. Begining n 1967, I believe, was the "2+2" style popularized by the Ford Mustang. Mercedes then offered the Coupe with a folding rear bench seat. It is great if your passengers are double amputees. With the front seats all the way back, there is zero leg room. But, my dog likes it just fine.
It's true that, living in Florida, you have to be a good meterologist and pretty brave to venture far from home with no top.
I think that the lack of the top hurts price a bit, but it is still such a great car and with the roof on, it parades the unique characteristic that gives the model its name.
Ray
'68 280SL 4-spd Coupe