Orbix 6.3.5 was tested with GCC 4.4 on RHEL 6. We have not done any testing with GCC 4.1, so we cannot comment. It may work and I would be interested in hearing any feedback from the community if anyone else has tried this.
I think we can only say it is not known not to work... if that's any help. I know that's not great help - if you can move to GCC 4.4 at all I would suggest you do, since that is what most other 3rd party libs on RHEL 6 will support.