I have Audacity & Magix whilst they are both pretty good they don't offer all the functionality I require.
The main use will be cleaning/mastering & removal of audience noise from live recordings
Can people recommend some others worth looking at?
Like mentioned here http://forums.macrumors.com/showthread.php?t=595581, it's kind of magic you're looking for. In order to function properly the program should be attached to your brainwaves, to cut off what you want to cut off... but a program doesn't really work that way. It doesn't "think" the way you want it to think. AI is still ahead to come... Noise reductions are available, but they are much simpler by construction.
I'd say the only way is the hard way: you have to analyze audio waves and "hand pick" the ones you want to be gone. You may, certainly, find help with professionals among audio. "Go pro" should solve a lot. But there is a lot of heavy work --- you need to carve the stone.