It is a good and interesting poll, but I don't think a full expression of the number of people using v1 or CMX or both.
beteljuice tried to get a current Cumulus user list by his "Unofficial Users Map" but unfortunately not too many took the bait and now that is no longer.
The visitors to the forum and then this thread is likely highly biased to CMX users. CMX users are more active due to now also includes the Ecowitt, Pi, and ongoing development. C1-only users are likely happy with what they have and don't visit too often. But I am still impressed on the questions by C1 users and most often it is their only or more recent post (and visit).
To show the visitor interest on CMX, the zip download data in the past 90 days :
b3215 597 downloads in 8 days
b3214 677 downloads in 17 days
b3213 980 downloads in 19 days
b3211 634 downloads in 8 days
b3206 738 downloads in 14 days
b3205 1016 downloads in 19 days
b3204 274 downloads in 2 days
b3203 432 downloads in 4 days
It is interesting to watch when a new release is announced and how quickly the downloads occur.
Possibly a number of downloads are just to have the current version rather than also doing an update.
The count for Mark's first b3044 is not available (likely due to volunteer beta testing) but from b3045 dated 2018-12-24 with 26 downloads and b3046 dated 2019-01-02 with 1288 downloads, and b3047 a month later at 1147 downloads, I would expect a lot of C1 and CMX-beta users were keen on the new features and platform.
There was a time when WU had a list of the number of users for the various software uploads to them (user specified) and from my memory that Cumulus number was just somewhere under 1,000 and very much in line with the other 2 or 3 primary weather programs at the time.
p.s. I have CMX b3000 to b3044... and v1 2013/07/13 to latest if anyone wants
Enjoy,
Paul