I contacted WFTDA at the address on the site (
sponsorship@wftda.com) and they sent me a summary of the survey results. Here is the part pertaining to the men's derby question:
Current skaters show a greater support for men’s roller derby than those not involved in the sport. Thirty-eight percent of skaters support men’s roller derby at least on an equal level as women’s derby, significantly more than the 21 percent of fans who support men’s derby.
I think it's interesting that there are differing levels of support between skaters and fans, but I can imagine that there are many fans who are simply unaware that men's derby exists. My first exposure to flat track derby (and any kind of roller derby) was through a men's and women's double-header, and I live in a geographic area that has multiple men's leagues that actively bout each other, but I realize that I'm probably atypical (please, no jokes).
They surveyed nearly 10,000 people. Half were skaters, half were fans. If anyone wants the summary, send me a PM with your email address and I'll forward it to you. It's a Word doc. They said it was no problem if I shared it.