It seems you've already found http://www.iana.org/assignments/multicast-addresses
, so you've done the right thing by picking an address from the 239.255/16
range.
As those ranges are entirely for site-local use it's no ones else's business which particular address you pick, but you may need to coordinate with the network manager (assuming that's not you) to pick an alternate address pool.
As others have suggested, just make sure there's an easy way to change the address just in case it does conflict with another address on the local LAN.
If the multiple applications issue becomes a problem, provide a (locally) well-known multicast address which the applications can talk to which will issue unique local-scope IP addresses for clients' use.