No, I haven't been hit. I try not to pay a lot of attention to SEO (while getting all my technical stuff in good order), and I try to pay a lot of attention to users. I'm also working on a multi-year plan - i.e. when I launch a site, I don't expect it to come up to potential for at least two years. I prefer to be the tortoise than the hare.
I also believe - strongly - that most SEO issues start with the business model. So I make sure mine makes sense. I'm never gonna try to compete with Amazon on books.