I should have a definitive answer in 2 months as we are moving a site to this configuration. Meridian rls 25.4, Symposium SCCS v4 with Genesys v5.1 Outbound running against SMLS v4 using a v6.5 TServer!!
Jealous?
Will let you know how we get on, but no design issues have been raised concerning the compatability. We are not using Genesys URS though so this may change things?