After a local shop dropped the price of the Varia Vision by 100€ (to €200) I took the plunge and bought one. I've now tested it running the XC skiing activity on the watch, and here it worked flawlessly. I didn't get any radar dots on the watch, but got both the data fields from the watch and the radar dots (and vibrating notification) on the Varia Vision. I have a Fenix 5 running FW 13.30. No problems with anything disconnecting (short ride of about 20 minutes).