Congratulations! I'm glad you took snakeeyes advice! I consider that one of the very best deals on a very high-quality speaker! I don't know how it will match up with your KEFs, but I consider that ceramic tweeter in the same league as my RAAL ribbons or my Focal Be (both are much more expensive) and Canton did a pretty fine job with the crossovers!
You will be impressed by the build quality!
IMHO, this is in a league well above the Q150's! That might not be totally ideal for sounds that pan across your front soundstage, but for clarity of dialogue etc I can't see you going back!
Let us know how you like it!