I'm also running a server on a Comcast business service with a static IP. My service has been really stable. This must vary on area. Also it seems if you're on business class, the techs take you more seriously. When I did have some stability problems the tech they sent out did a few tests, then went to the entire first floor (5 units) of the condo building with big sticky notes telling them to schedule a service appointment or have their service blocked.

Getting reverse DNS was easy. Following the directions I found via Google I went into the Comcast business service forums, read their pinned posts and sent a PM to the current service guy. He set the reverse DNS for me. It took about a day.

I've never had to worry about reverse-DNS, and I email thousands of fashion/media/tech companies around the world, big and small. Are there really servers that block based on reverse-DNS? I've never seen it.

It seems to be a flaw to have reverse-DNS block mail servers, since a single mail server might serve multiple domains. (My server serves email for multiple domains)