I've been using Gravel Kings on my daily commuter for the past three months and these tires have encouraged me to extend my commute to work and home since I'm having too much fun riding my route.
The roads here in Houston are heavily pockmarked with potholes and these tires handle them with no problems and just roll over them without any tremendous jarring feeling. On pavement, they roll fast and grip corners well. They're also a blast to use in fine gravel, they float and move quickly and sure-footed.
I'm currently using them with tubes and on 40 psi front, 45 psi rear and have had two punctures on the rear tire. First one due to a nail, the other due to a construction staple.
I just got these and did my first ride last night. I got them for my 3T for a set of winter tires. Road on a newly refinished road with chip seal and they are smooth. Took a few tries to get them to seat on my rims but i think that is the rims since i had the same type of problem with the schawlbe that i had on the rim.