We use Dag's Cfengine RPM on 4.x and do package management with it.
The only trap that we've encountered, beyond those already listed, is that cfengine executes shellcommands with umask 077, and many RPMs don't install correctly with umask 077. To fix this, make sure that you always add a umask=022 option to any rpm shellcommands.
thanks all - useful tips and something for me to digest slowly i think
cheers