Found the Problem :) In the OpenVPN Servers ettings under Advanced I added push "route 192.168.1.0 255.255.255.0". Now teh VPN Client can route correctly.
I found this post which says the author accomplished exactly what I'm trying to do but unfortunately doesn't go into much detail:
http://quintinsmits.com/2009/09/14/bonjour-mdns-via-openvpn-on-linux-with-avahi-deamon
I tried switching from tun to tap but was still unable to view bonjour services.
Actually it's perfectly reasonable, as an IP alias is an additional interface IP directly assigned, and that requirement is already known for the main interface IP.
CARP VIPs are the only exception to that, since they alone can be shared.