Personally I love mastering in Sonar. Mix, then master...sweet and simple. To make a redbook CD, which I haven't needed for a while, Cake, I'm not sure still have Pyro Audio...which is great for assembling a redbook CD, you also get the MP3 encoder, which is bad. Or there is Soundforge, which also has a cut-down version. I use both, but I think people need to think around the box when it comes to mastering in Sonar. Just use it as a mix, master and bounce down tool, then create CD elsewhere...or that is my advice.
Ben