I just recently (2 days ago) upgraded from FC3 to FC4. I agree that the boot is faster. My main reason for upgrading is that I wanted some newer software (Kyum) and the mirrors only had it for FC4 and not FC3. It was also a good time to upgrade kernel to latest 2.6.14 and Nvidia drivers to 8174. All of which went really well once I had the kernel source.

The upgrade also upgraded MySQL to 4.1 and PHP to 5.0.4. This has played some havoc with some local scripts that I was running for development (now fixed), and has highlighted some of the issues to be had when my Hosts upgrade to PHP5. My issues were with Sugar CRM and OsCommerce admin interface. Playing with php.ini fixed most, and a small code modification (1 line) in osCommerce fixed the admin blank screen.

I would say that as long as FC4 installs OK on your hardware and supports all the service that you want to run, that it will be just as stable as FC3 if not even more so. I would think that if you put FC3 on then you will be upgrading in 6 months, but with FC4 you will likely be fine for 12-18 months before wanting to upgrade.

I vote for Centos 4.2 myself I've been a Fedora fan from the beginning but got tired of the unstable software and went with Centos 4.2. If I don't miss my guess it's fedora test field then RedHat uses it for their release then Centos repackages it for them. So what you end up with is RedHat enterprise relabled.

The downside for some people is that RHEL and CentOS do not contain the latest packages e.g. GNOME is 2.8 but the latest is 2.12.