My tested FTP via ramp test on TrainerRoad 3 weeks ago was 225 (after an 8-week TR program).
Yesterday I managed this on BigRingVR. The wattage average was 223 for the first 90 minutes and only dipped in the last 10 minutes due to spinning out on a steep (virtual) descent. It was hard but I felt fine after and think I could repeat today. The HR stats show I was never even close to my max of 178.
(https://i.postimg.cc/ZYdDBwpQ/BRVR-data.jpg) (https://postimages.org/)
You're both probably right in that I didn't push myself quite hard enough on the ramp test. But I also think there is a motivational factor going on whereby if I'm trying hard to keep a high average wattage on a VR programme with all the visual stimulation and chasing other virtual riders then I just push that much harder than on an interval session with recovery built in.
The question remains - which type will I get the most benefit from?
Don't tell me - a mixture of both? ;D