When deploying Coherence on OS X please be aware of the following:
OS X defaults to running multicast over IPv6 rather then IPv4. If you are running in a mixed IPv6/IPv4 environment you will need to configure your JVMs to explicitly use IPv4. This can be done by setting the java.net.preferIPv4Stack system property to true on the Java command line.
On OS X it is suggested that each Coherence cluster use a unique multicast address and port, as some verions of OS X will not take both into account when delivering packets. See the multicast-listener for details on configuring the address.
Generally Coherence prefers 2MB or higher buffers, but in the case of OS X this may result in unexpectedly high kernel CPU time, which in turn reduces throughput. For OS X the suggested buffers size is 768KB, though your own tuning may find a better sweet spot. See packet-buffer for details on specifying the amount of buffer space Coherence will request.