No, I haven't, and I am sure it is possible to do reliable real-time with those. It looks like all of those are commercial solutions (no open source).

I remember reading a paper about the IBM implementation (I assume that it turned into WebSphere). If I remember correctly, you still need to do some memory management like allocations up front compared to a "normal" Java program. Those guidelines seem a lot like what game programmers in Java end up doing.

I remember in college for a project that a team did a ping-pong playing robot in Java. It worked fine for maybe ~15 seconds then suddenly froze for a GC pause.