This is a pretty healthy conversation but I can still add my $0.02
I hosted my own email server (webserver etc.) from 1995 to 2005. It was very enlightening but eventually grew to be a big pain in the ass. The last straw was a power surge that fried the motherboard. (raid and backups can't help with that) and looking at the the time and effort of getting a new hardware (and getting more redundant hardware) I decided to go with a hosting service. Eventually I pointed my domains to gmail.
Every geek friend I know has at one time hosted his own email. I'd be hard pressed to find a techno-nerd worth his cred who hasn't tried this. I also don't know anyone who has continued to host their email after a number of years of feeding and caring for the server beast.
I think the big issue is figuring out where to separate you hobby from your job. If you have a classic car in your garage that you like to tinker with is fine. If you decide to do you daily 20 mile commute in your classic car you're signing yourself up for some headaches as there will be days that you will need to bumb a ride, take a bus or taxi, etc. Hosting your own email is like commuting to work in a car that only you are able to fix in an environment where there are no buses, taxis or other cars. You have to be prepared to drop everything at a moments notice to fix your email server.
You can have someone else host your hardware but then ask yourself, why not have someone else configure and maintain the software as well?
DIY is great but realize what your signing up for if you want to DIY a critical system.