0.77M of Alexa top 1M were not in my list.
$ cat alexa alexa myset | sort | uniq -u | wc -l
I mined 25,842,205 additional domain names.
Feel free to grab a copy of our domain list. The "All domains with NS records" is the one you want. Has 191 million in it.
(and yes.. now i see that you mentioned it in the article.. took me time to get there)