My personal experience with Mixed In Key messing with tag info after analyzation is that it shortens the title, changes the genre & removes track number tags of many of my songs. I put lots of time into the tagging of my tracks, so the fact that I run hundreds of songs through MIK to find out later that info has been changed in places that MIK shouldn't even be tampering with on any parts of my library is frustrating.
I've made sure that the software doesn't change info in said places in the MIK 8 settings. Here's how I have them personalized.
Under "Update Tags": "Update common tags" is checked "What to Write" has "Write the key and tempo" selected "Where to Write It" has "Overwrite comments" "Update custom "Initial Key" tag" is checked "Write energy level in front of the Grouping" is checked "Update "Tempo" tag" is checked "Keep existing tempo values" is not checked
Under "Rename Files" "Should MIK Rename Files After Processing?" has "Do not rename files" selected