I don't encode at 320. I encode at VBR up to 320, which usually ends up averaging about at 190.
I am aware of that r3mix website, and have actually had a bit of correspondence with one guy there (a year ago) if I remember correctly. Measured tests are VERY useful, but in the end, it is my ears that are the most important to me. The point is I don't listen to signal sweeps so it's not very relevant. After all, MP3 is a convenience format for me - I do own all the original CDs after all. I did say though that Xing is as good for most stuff. I don't make any claims that it's perfect - just fast and convenient.
As for the other software, I'll check them out. RazorLAME doesn't look like it would suit my needs, but EAC looks interesting now. I had checked it out a long time ago, but back then it was not as flexible as AudioCatalyst 2.1.
By the way, with the best settings, how fast can you encode with EAC? With my Celeron 880, I can encode at about 12X on the fly with my best drive, or about 14X with my other one. Speed of encoding is of high importance to me, since I have several hundred CDs that I'll need to encode.
What I have discovered though, the original CD-ROM/DVD-ROM drive is an important a choice as the actual MP3 encoding software.
After testing several, my best one is still my Panasonic CR-584B drive - no "jitter" correction software or extra jitter-correction hardware (in some Plextors) required, and is still better than many drives (like the Pioneer 104S) which are supposedly top notch drives.