I was thinking this might be related to http://forum.mikrotik.com/t/connectivity-issues-after-upgrade-7-17-2-7-18-7-18-2/182602/3
But the trouble is slightly different. I had no trouble bringing up a VPN on 7.18.2 even GRE/OSPF worked, but sending traffic to a host behind my CCR2116 just stalled out, but sending traffic from a host behind my CCR2116 worked just fine. 7.17.2 and 7.16.2 showed the same issues. Once I go past 7.15.3, things break.