I've come across some issues with Lync 2013 and Windows Server 2012 R2 (TLS fix is applied!)
Working on a project with 2 Pools and a number of SBSs and for some reason every couple of days the users on the SBSs go into Outage Mode. After reading the logs I can see "TLS negotiation failed" and after that the SBS can't talk to the FEs anymore, can't even browse to any Web Service on that FE.
Haven't figured out what's actually wrong but rebooting the FEs seems to be the only way to fix it.
I'll post more info once I have it but for now I would stay away from 2012 R2 if you are thinking of deploying SBSs