Actually, maybe the question is whether SME 8 will support or be upgrade to 5.2 or 5.3 in the future. Like what you said, the developments take longer than other distros and users may think of switching (e.g., to centos 5.6).
I'm using sme 8 b6 for our production intranet server and is very happy with it. SME is a very stable distro and quite. If users will have a assurance that the project will not die, then people will stick to it.
In my case, with my current installation, I can't install php-intl which is being checked by moodle 2.0+. I've searched for solutions but to no avail. Shouldn't this be as easy as yum install php-intl?
Kwak