It appears there are at least 8 on the road if this is credible.
ANY spotting of additional Xs on the road is a good thing. Based on the screen shot it appears it is a Founder's X. Why? Because it appears that it has a set charge limit of 72amps when not supercharging. We know, or think we know, that Founder's X have the 72amp onboard charger while The NASales team at Tesla reports the SigXs will have 48 amp chargers
Number 8 was delivered over a month ago. There are more than 8 on the road, just their owners don't post on social media and it's hard to get the VIN of every sighting.
The best spotting of an X will be the one in my garage. Any prior to this doesn't help me much (except the hint my slot in line may be getting closer).