Migrating projects from Kontakt 6 to 7

I thought I'd migrate my projects in Logic from 6 to 7.

What I was surprised to discover was that in particular, when opening certain Sonuscore The Orchestra 2 Multi's in Kontakt 7, with all other settings in my project being the same, the levels of instruments are quite different, making my mix not sound right. I haven't investigated further yet, but if I have to go through and tweak lots of settings to get it to sound the same, I don't thing I'll bother, as I thought it would just be a matter of changing the plugin and re-opening the instrument on the already saved multi.

Have I missed something about the backward compatibilty of Kontakt versions?

(I just wanted to do this for housekeeping, and make my life easier in the future)