Is Stages SB200 lighter than SB20?

Yes. Stages says the SB200 weighs 32.3kg. SB20 weighed about 57kg according to DC Rainmaker.

Does Stages SB200 still measure power at the cranks?

No. SB200 calculates power at the brake, with a claimed accuracy of +/- 1%. SB20 measured power at the cranks.

No. SB200 uses Bluetooth and Wi-Fi only.

Yes. DC Rainmaker reports that Stages has manufactured SB20 parts again and reopened its support lines under Giant’s ownership.

Cycling News Smart Trainer

Stages SB200 is about 25kg lighter than SB20, moves under the rider, adds Wi-Fi, lever shifters…