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.com
I have been with Live-books for a long time now and always found them helpful (sometimes a little slow, but always produce great results).