hmm, how much hevier are the 750 rears then the 550s ? my 636 rear tires and rims are DEFINITELY heavier than my 550, especialy with the 200 rear tire compares to a ruber band tire on those spokers, my r6 was heavier too... im not saying your wrong or im right orwhatever im just saying from my experince with my bikes
not sure I have never weighed them back to back. I imagine there is a difference because the 750 drum is larger and the rim is wider. The SV rims are not that much wider than what is on a 750 and the tire may be only 20mm wider (a 150 vs. a 130), plus you don't have to run the SV with a tube.
When changing wheels the biggest weight savings comes in the brake components, espcially in the rear. One kawi h1 caliper and bracket weighs almost twice what an fzr600 caliper and bracket weighs. Same with the rotors. The forks may be about the same but the modern forks are much better.
some mags are lighter, some are heavier, depends on the bikes being compared. In the end it is the total package weight that you need to be concerned about. Even if the total package weight is the same the brakes and forks will be better with the newer components.