One thing I forgot to mention: while you're considering Debian and Ubuntu support, make sure to also take into account MediaWiki support.
Even if we upgrade our minimum PHP version now, older versions of MediaWiki with the 5.3 requirement will still be supported and receive security updates. So the only difference will be that people running Debian oldstable will be locked into our older version and not be able to upgrade to bleeding edge MediaWiki, which they probably won't do anyway considering they haven't even upgraded their Debian. :P
-- Tyler Romeo https://parent5446.nyc 0x405D34A7C86B42DF