Hi r2d2Melv,
Thank you for your posts and welcome to SEBLOD forum.
You can download an application from "Construction => App Folder". Then for your question, it's depends on the seblod elements (plugin, template, variation, ...) in the application.
If at least one element is not compatible from joomla 2.5.9 to joomla 3.1.1 => all application is not compatible.
Regards,
Mehdi.