I have installed the sj_expo quickstart on my local Mountain Lion Server machine, and for the joomla 3.1 version, I find it exceptionally laid out and is truly responsive. I don't understand why the main content is core joomla rather than k2 content, in the quickstart, but I will soon import all of the joomla content into k2 to see what it looks like.
I have installed JomSocial 2.8.4.2, as well as the Tigra framework without any problems.
ImproveMyCity (slight problems, but it's the component and not sj_expo).
JDownloads (with core modifications).
Admintools 2.5.5
Akeeba Backup 3.7.7
I am seeing some problems with the template's internal "lazyload plugin" but I'm not sure of the cause. It just randomly stops working sometimes. If I chmod all of the permissions to 777, it seems to work for awhile, but then corrupts after some time.
I had to turn the lazyload option off iin the template settings to get the images to show up properly. 05/20/2013.
Walt.