Mixed in key is a huge time saver and essential for me! I use it to key samples, sounds, tracks and for all my DJ sets.
I have been Using Mixed In Key since version 3. It has made a huge difference in my DJ sets. Being able to pick the next song by choosing a song with a compatible key has nearly eliminated set planning for me. I now plan sets as I'm playing them and they sound so much better because the song transitions are harmonically compatible.