I need a little clarification too.
When setting a CNAME, it always asks for a host or subdomain. I don't see a way to point a domain name itself using CNAME, unless I'm missing something.
I know you can point www using CNAME, which would probably work pretty well, but I assume if someone leaves off the www they'll get something else, probably a parked domain page from the registrar.
Some things I've read seem to indicate that it's possible to point the main domain with CNAME but I haven't found how to yet.
I see that there are some downsides to doing so, though, since pointing the CNAME tends to take MX records and other settings with it, which wouldn't be ideal for this setup. I'm sure some people are using e-mail accounts with their domain registrars so if they were to point the CNAME of their domain to their blog their e-mail would stop working.
I guess one option is to point the CNAME of www to their site and then set up domain forwarding for the domain name itself and point it to www. I'm not crazy about that solution though.
The only reason I'm considering CNAME over A record is for the reasons sited above, your IP Address can change. If it does, it can be a huge pain because all your users have to change their A record again. It sounds simple enough, but for the technically challenged it's not, and in a scenario where users are paying for the service, they're not going to be happy.
A while back I had to move my network site to a new server because my host was no longer supporting the software version on that server, probably the operating system, I forget now. But it wasn't a case of changing hosts, just switching from one machine to another. Besides that possibility, I might need to someday upgrade to a server with more resources or something. If there was a way to stay locked in to a certain IP address it be ok, but it seems like something that can change too easily.
Do you have any ideas for a solution? I liked the possibility of using CNAME since it points to the domain instead of the IP Address, but it seems like it has some challenges too.