Hello Dario,
look at this thread:
https://openacs.org/forums/message-view?message_id=200201I think, you should be fine to start with alpha3 which might come this friday or monday! (Tracy?)
Site nodes and some bad performance queries should be your biggest concern, I suggest you to start testing (loading all the 80K users + plus the courses) with oacs-5-1 and report soon slow stuff and if possible fix them!.
BTW, do NOT use curriculum due bad performance with a bunch of nodes... (comment it from dotlrn-master.tcl)