Without a lot of information on their marketing plans, I would not want to advise either way. The reason I say that is on the Web, it's all links and nowone really cares if it is the IP number, a vanity name or a directory name off the ISP's server. I had no idea it ever existed. Yes, it will come up on the search engines. The unpublished stats do not look all that impressive for IBM, and a couple of others.
Service providers seem to do better than retailers.
In the case of John and Jason, it is important to have a vanity name because of the name recognition, etc. We're conducting our own annual survey at the NTCs and will be asking exactly that. Sven, That is so hard to calculate. Who knows how a visitor came to your site. Some advertising is done in such a way to track which print ad the lead came from.