OK re-enabled slbd today and it works, even after slbds ICMP poll states DOWN and filters are reloaded, daemons stay alive. I think the problem is related to two things:
one interface changing (dhcp, dis-/enabling)
reloading openvpn daemons via the stated command (sh killall -HUP openvpn)
The SIGHUP seems to kill a random number of daemons while restarting them (whysoever). ATM I'm ordering new CF-cards to try a clean new installation on one of these and do some modifications. If anyone knows more about that "restart phenomenom" or has problems alike I would be glad to hear some comments.