I love the 3K on her own. I'll use the 4K together with my PGC, DD-2 delay & Chroma Chorus to get that 80s "Landau / Lukather" tone which I've always loved.
I was using the MP Sky Blue OD to get this tone but I had to let it go because I couldn't keep so many pedals, but when the 4K came along, it surprised me that I could use it to get almost the same tone with the set up I have.
So many BJFEs, so much to enjoy! The combinations are endless.