I think some of this comes down to the quality of content too and who the writer is. That can really skew some of these tests. I am a subscriber to Patt Flynn's site, and yes there was a double optin. Was I reluctant at all because of this? No, but the reason is because Pat Flynn's content is so amazing I didn't care lol. For people with more mediocre content, that double optin might hurt you. But again, only way to know is to test.