One wonders how long it will be before Bookbub is also selling ebooks. An advertiser becoming a vendor is certainly interesting.
I don't think they'll sell ebooks because many authors use BB to boost their ranking on retailers...
Chirp has the problem that won't boost visibility on regular retailers.
Unless the effectiveness of their featured ads is cut by 80%, I'd still take one if I could get it.
If Chirp has alsobots and bestseller lists, it's just another vendor. If I have a feature on Monday, and on Wednesday I'm getting sales because I'm in Tuesday's feature's alsobots... I'd take that.
But we won't know until we know. Their PPC ads are pretty lame, IMHO. This could be like that all over again. Or like the Nook advertisemageddon.