Wildbow: I do think discussing stats can be tricky. If you are going to be counting on ad revenue in the future, past data might be one of those things that could bite a host, specifically if your future strategy is all going to be about "sponsored linking" like Penny Arcade currently does. (SO I wouldn't reveal too much if you're going to be ina position of negotiating in the future.)
Ironically,Project Wonderful already kind of forces some transparency. I hope people are aware that even if it is off a bit here and there, having an ad on a site still speaks a lot about a site's stats. (And people like me are there, looking at it with great interest.)
For me - the data sharing serves a purpose of painting or trying to paint the broad picture of online fiction. Right now I think the new folks entering this platform (like those with Jukepop) are a bit too optimistic about readership. I feel badly because I feel that this leads to discouragement, more dropouts, and a worse picture for online fiction overall.
If possible, having a few case studies out there might help reset expectations and help people be more thoughtful on how/where they promote.
Uber: sometimes this has a lot to do with layout and what your primary promotion is about. it's hard to say... but glad that tip proved interesting!