I think liveBooks or some of the other Flash providers are fine for portfolio presentation. My business model consists of photographic print sales, stock image licensing, workshops and tours, e-books/iPhone apps, and assignments. The liveBooks site just isn't built for this kind of business whereas the Photoshelter/Wordpress sites can easily handle all these different aspects.
I would just add you can accomplish a lot with Live-books other than portfolio presentation - but it does involve customisation and costs over and above the standard templates. I worked with live-books to custom develop a workshop and expedition layout for the trips I lead that works for me. Of course, with this sort of thing its highly personal and comes down to what you need and want. As always YMMV.
www.photographyexpeditions.comI have been with Live-books for a long time now and always found them helpful (sometimes a little slow, but always produce great results).