Thank you for your suggestions,
I would like to use standard functionality and I don't want any potentially unstable solutions.
I have a little experience with using Alfresco so far, but I don't really see, why Share site is something so much separated form Alfresco?
What I like about Alfresco is good user rights, user groups, clean interface without all "news" all over. Users often got lost because they couldn't see "site link" lost among other information.
On the other hand Share has blog that we need, and very nice document preview functionality. Whats more I get a summary of recent activity (who added what etc) But I don't have detailed access rights for document library.
For me, at least as I see it now, I would need a nice mix of those two but with single, common interface.
(Alfresco document management + document preview + blog + doc/blog activity report)
For now I'm planning to use ONLY Share (with several sites) for all my needs.