In terms of maintenance, you're going to get a lot more pain out of GNU/Linux than you would out of any BSD or SVRX Unix. I wouldn't migrate to GNU/Linux.
If you don't tinker, then a system can run infinitely, but you might be at a disadvantage running an older build. For example, a new version may have performance enhancements that may improve your productivity. To keep system up-to-date, you don't need to learn every single element of the Unix command line. You only need to know a few commands. On FreeBSD, you need to know five variations of the same command to update the system. I'm sure it's even simpler if you use binary updates.
http://quickdc.sourceforge.net/
Check that link out for your dc needs.