I manage two separate environments:
Single-instance JBoss 4.0.4.GA
Two-node cluster JBoss 4.2
Both run well on the Sun 1.5 VM, but I have noticed that JRockit is far less prone to OOMEs and generally requires less tuning and monitoring in my test environments. I understand that JBoss certified JRockit 1.4. I use 1.5 features and all seems well, but I'm just looking for some reassurance from JBoss or from the community. I'm especially concerned about the cluster, as I'm sure it exercises more of the VM than the stand-alone model.
JRockit should work just as well as Sun's JDK.