Nancy, I dated my 640-2(which I've not started a thread on yet) to 1954, but these two machines were probably from the 70's? Bernina has a way to date the machines using the serial #, but it doesn't matter to me with these two machines.
Bernina is most like Elna in their design, IMO. Which makes sense as they were located near each other and probably shared the same people working for them at some point. They aren't as quiet as an Elna, however, but Elnas have insertable cams and Berninas have built in cams which can add to the machine noise level and weight. The star series Elnas (62 C and beyond into the Carinas) are whisper quiet.
I don't find Berninas to be as hard to work on as Pfaffs but the parts and availability of getting them is sure up there in cost along with all other European manufacturers.
The vintage Pfaffs also lack the ability to do a serpentine stitch, but Viking has it on the 'B' cam, I believe!