I have a lot of projects with instances of Kontakt 5 loaded (and a few with K4). Over the summer I will probably take advantage of the sale on Komplete upgrades and will find myself with Kontakt 6.
I remember hearing something about a feature that would let you replace older versions of a plugin with newer versions. Did anything ever come of that, because it might be nice if I could effortlessly replace the K5 instances with instances of K6.