Follow up
Recent weight loss regime: Front EBC Vee Rotor (~1lb shaved), center drill front/rear rotor bolts (2g's off each bolt, 20g's total shaved), rear Galfer wave rotor (~3/4lb shaved), 520 chain conversion (~2lbs shaved).
Very noticeable felt difference in handling or "flickability" in corners. Feels like a different bike. These were the only things done this go-round, so I have to attribute the weight loss to it's felt increase in side-to-side cornering quickness (S-curve changeup). As far as any other increase in performance, I can't say I feel it. "Might" feel "less sluggish" though, so that's probably the seat of the pants felt change in accel.
One huge benefit with braking though, the front with the Pretech 6-pot, feels little changed from the stock disc, the rear, OTOH, actually feels like a brake now! Seriously, the rear was rusty and cobwebbed for total lack of use. Because it was useless. Locking it up in my dirt driveway was a rarity. Now it actually does something and slows the bike. I can lock it up on tarmac (would have to stand on it before) and easily do so in dirt now. That was something I did NOT expect (that a simple disc change would make such a difference in braking efficiency).
If I had to do all over again, the rear disc would be the first thing and considered MANDATORY, the rest, maybe not so much.