in my experience
The dependance on the 'www' prefix can lead to a certain problem I've seen at many sites. That is that the non-www version of the domain has no DNS record for the web site. So, if you hit the www version of the domain name with a browser, everything is cool, trash that prefix tho, and often, you'll get nothing. Pair.com (my host) is great for the simple reason that they anticipate the user's/customer's needs by adding records for the www and non-www version of your domain name (and they do a bunch of other cool stuff too).