Latest strongSwan from brew repository works good on OS X. But most painful thing is connection restart after changing WiFi network. I need to reset it manually in most cases. Even low Dead Peer Detection (dpd) timeouts didn't help.
Here is this part from my ipsec.conf:
# Always up
dpdaction = restart
dpddelay = 5s
inactivity = 10s
keyingtries=%forever
auto=start