Yes, very possible to develop nice sites in Website Baker (how about
www.actionchildren.org and
www.michezoyouth.com 
). The only real issue I'm having with it at the moment is that there are a couple of bugs/issues with some modules, which is kind of annoying when trying to add functionality to a site. One of the things that has already got me interested in CMSMS is that you have a gallery built in, which works right out the box. With WB you have to add gallery modules, and I've had a lot of issues with them that seem to be attributed to my localhost environment, but since everything else works fine, and CMSMS runs fine, it seems some further annoyance.
Definitely not saying WB is a bad product, and supposedly I can install an Apache environment with Xampp or Vetrigo that will solve the issues I've been having, but it is a small issue that has caused me to rethink.
The one thing that WB does have over CMSMS is that you can set individual pages to have specific admin user access, so for example you could allow someone to only access a single page, i that was their area to manage. Overall the two seem very similar, both in how sites are created, how areas are managed, and in overall functionality and ease of use. I'm now just looking at things a little more closely, as I try to work out what would really be best for paying clients.
Thanks for the replies so far, much appreciated.