I can only tell you my experience, and I now own both the Mag 800 (early adopter) and Kinetix 800 (also early adopter).
Since I added the Kinetix, I don't feel anything is missing from my arsenal.
I use the Kinetix for my Zeppelin stuff, and the Magellan for near everything else, including the rare occasion I double on DB.
The warmth of the Mag has been "it" for me for many years.
the extra kick from the Kinetix as a rock head, well that's now "it" for me and my needs when I really want to rock and still sound incredibly articulate (so much that it makes me be a better player). That's my experience.
I've tried many other heads. Including some very good ones from Berg and Boogie. This is all I need....well, and this lamp.