I have a KA-SLNG and its neck is thicker than the standard Kala soprano neck, possibly because of the longer scale. I can't say it's overly thick, but coming from guitar just about any uke neck is going to feel slight.
The SLNG is a very nice uke which impressed me greatly when I got it, but I just got an aNueNue Mini Concert (same thing as a super or long-neck soprano) and with the same Aquila strings its tone is noticeably warmer and more "solid wood" sounding. I have a mild structural concern about the aNueNue (noted in another thread here) but I haven't yet decided whether it outweighs the uke's assets.
I wasn't aware of the KPK ukes. I just looked at their website, and I'm very impressed. I may just have to look into them someday.