Personally, I get very little feedback on my fics, so I'm likely to recognize a name or not if I see a rec. With more read authors you're probably right. I was also thinking especially about Remix, where so many people were talking about the same group of stories in a short period of time, so it becomes much easier to see who's reccing your story and to notice if they also sent you feedback. (This was further complicated by the trend of "correctly guess which remix I wrote and I'll make you something nice," as I know at least one person who had people correctly guess her fic but not send her any feedback on it, which she found profoundly strange.)

Certainly authors would be happy to get either. I just know if I saw a rec from someone but hadn't received any feedback from them I would feel weird, like, "They liked it enough to tell their friends but not to tell the actual author?" Because I know if I like something not only do I want to share it with other people but I want to tell the creator that I liked it.