After spending some time comparing what I can do with both distros, I come to the conclusion that I must be prudent before I use ClearOS. The list of contribs for SME-Server is the main indicator of what I mean. It is impressive and I did not find a contributor's space in ClearOS.
Reading the ClearOS webconfig php sources, with the little knowledge of php that I have, let me think it is not easy or organized to receive contributors addons. In other word, ClearOS does not appear to be contributor friendly like SME-Service is with no doubt. As a dev-team usually works on ideas they approved, with SME-Server, someone can work on it independently with no problem. Recent examples of this: zarafa, openvpn-bridge, ejabberd, etc.
With a single line of instructions I can install Scuttle, and with a few ones, I can install eGroupware, etc...
If someone needs only what ClearOS offers out-of-the-box, it's a good choice. But if we need an open-minded system, SME-Server is better structure to adapt to new software.
Also, being able to do almost everything from the command line is a big point in favour of SME-server for those who have to maintain many sites, remotedly.
It is obvious that SME8 is overdue and that it hurts to certain point. But "jumping the ship", as someone put it, might not be a good advise. Unless contributors find their way into CLearOS's menu system, the strenght of SME-Server is in its contribs and howtos.
For a user like me, it translates into a system that will adapt to needs that I don't know about, yet.
My 3 cents...