Why do you think it's inaccurate?
I don't know why I am bothering, but given that there are 100 X1000s in circulation and each is running OS4.1, then to have only 100 OS4.1 users is clearly inaccurate (given that only 6 X1000 owners have registered on maw2k's map).
If you are a fan of extrapolation, and given that 6% of X1000 users have registered, we assume 6% of all OS4.1 users have registered, then that would put the OS4.1 users around the 1700 mark.
Either way 100 OS4.1 users clearly underestimates OS4.1 usage I am sure you can only agree.