T-Mar is right. I just replaced the rear derailleur on my Medici . It came with a Patent 74 Nuovo Record and I put a Patent 82 Super Record just because the bike is a 1982 model. When I held the derailleurs in my hand I couldn’t feel any weight difference , it would take a scale. I am sure it is even more true for the front derailleur. The shifting and performance on my bike is the same after the switch. To me it is just to make the bike more correct . It is more like a visual preference than anything else. The only significant weight difference I have seen between SR and NR components is on the Superleggeri pedals . The SR with titanium spindles is noticeably lighter.