I look at the spec sheet of each succeeding generation of lenses. If the lens is like 1kg or so they dont really bother cutting weight. Anything heavier than 2kg and there is an incentive to make it lighter.
Like, if I knew the 500/4L IS version 1 would have the same weight as as the 600/4L IS version 2 I would have delayed purchase by 14 months.
Only tangible reason an owner of a current gen lens to upgrade ot the newest version would be performance improvements or in this case weight reduction improvement using better material science.
If you havent had a hand in the supply chain or materials R&D then I get the skepticism.
But you are referring (at this moment) to super-tele in the EF line, and not the non-existent RF line. As far as RF super-tele, you have absolutely no idea yet what they will weigh.
Then I kindly turn you towards a look at the other RF lenses that are already here. What is lighter than an EF 85mm f/1.2L, EF 50mm f/1.2L, EF 28-70mm f/2.8L? Any of the RF's? No. Sure, the RF 70-200 is lighter than the EF version. Isn't that just about it? The Canon EF 24-70 is 95gr lighter than the RF version. So where is this advantage of RF over EF? I don't see it when it comes to weight, which for some reason, people keep trying to claim.
I think the #1 selling point for moving from EF to RF is the weight reduction.
You claim there is a weight advantage to RF. I don't see it.