Re CDA, just a matter of convenience. CDA does an excellent job of mastering including printing cue sheets which duplication houses need. But for most people it doesn't seem to offer more than Vegas or Nero does.

As for noise reduction, I don't know of anything else that does the job as well. It still cannot perform miracles. It can get rid of annoying noises in well recorded audio and give you very clean audio. It will not save really bad audio, noises that cover the whole spectrum are impossible to remove usually.

I was able to buy SF7, CDA and the NR2 and Acoustic Mirror plugins for the price of SF7 as a show special some time ago. More than I'll ever need but it doesn't hurt to have a few more tools. Only wish I had time to master the art of using them better.

Perhaps we could give you better advice if we knew just what you were trying to achieve.