OK, one important thing I will add here: NEVER, EVER, use a multicomp, an exciter, or any dithering software you have available on a final mixdown on the Stereo Out bus if you are sending it off to a mastering lab. This will limit severely what they can do and - without exception - if you have chosen the mastering facility well - they will have better versions of these types of things on hand. Sad but true.
On this note, FWIW, I talked with a salesperson at Waves not too long ago and he said something that I still ponder. He said he was using Cubase and he was sending things off to a quality mastering facility. He said that the long time engineer told him his mixes were getting pretty good lately, that he only had to change/add a few things. This was high praise I think and an indication of what Cubase is capable of with a good ear and some serious effort. All of which has nothing to do with mastering your own recordings… Just sayin.
Yes. Smart bypass…to my knowledge not found in any other editing/mastering application, and for me a very valuable tool when a client is listening over my back. Smart bypass eliminates any db bias so you can concentrate on the A & B differences. It isn’t instantaneous in that you have to “sample” a few seconds first and then compare.