If you're prepared to believe that...
I'm going to take a stab at estimating the percentage of the market that 1,125 respondents represents, and I'd say it's less than 1% (assuming each represents one company). So if you're prepared to believe the stats that come from 1,125 respondents, it's reasonable that you should believe the results coming from a similar number in another survey (980 responses), correct? That survey reveals Lotus Domino to hold 83% of the market.
http://www.computerwoche.de/index.cfm?pid=436&pk=1470&op=lst
Flawed? Probably no more than any other survey that takes in a tiny fraction of the market. Why not walk round Microsoft's campus and then come to the conclusion that the Zune leads the market over the iPod?
As for people who say "I used to use Notes, I didn't like it, but I'll stick my fingers in my ears and say la la la rather than hear about the improvements"... they just sound a bit childish.