Please don't get wrapped around the weight savings, they're minimal.
Dry 13-18 Roadster 734 lbs
Dry 19 TFC 648 lbs
Wet 13-18 Roadster put on a diet 717lbs (about 640lbs dry).
What remains to be know is how readily 50-60 lbs can be she'd from the 2020 bikes. The exhaust may achieve that on it's own, who knows, as we all know the 14-18 exhausts are boat anchors. The engine will almost certainly weight a good chunk more on the 20s. So if they saved a lot on the stock exhaust there won't be much to easily shed, but if the frame is truly most of the saving, getting a '20 under 600lbs dry will be very possible, 630 wet may be achievable.