I put these tires on for the purpose of having a do it all tire, and they do just that. The smooth file center is perfect for hard surface, and allows me to maintain a road tire pace when on blacktop en route to trails. The lugs provide all the grip necessary when off road, I can feel them grab on wet soil, loose gravel. These are maybe not the best for extreme muddy conditions, but for wet winter trail riding they are sufficient. I know they are designed for dry conditions, but this is the PNW and I don't enjoy the rolling resistance/weight of fully lugged tires. They are also lighter than most touring all-road tires, the weight is accurate. I have a 32 in the rear and a 38 in the front, coming in at 720 grams for both. I also like that I can jack the PSI up to the max with tubes. The only downside is if you do any urban riding with road debris such as broken glass, you will get flats! I have had four since putting these on, glass shards go straight through the center file tread with ease.
All and all very well. I ordered the 38's and wish I would have gotten the 40's. 38's measured out to be barely 37mm mounted on 22mm (internal measurement) rims. That being said, great all around tire. I am mostly a road rider but put these on my winter/gravel bike. For me these will still likely see more pavement than gravel but performed very well on spirited gravel rides. Grip was better than expected on hard pack, loose and even on the chunkier gravel sections and they also shine very well on open road. My only gripe is purely vanity reasons, they are not very aggressive looking mounted, honestly have the general appearance of a more "tourist" wide road tire. Think the WTB Byway is a similar tire with a bit more sizeable nobbies on the side. Anyhow didn't effect performance of this tire. Would highly recommend for a great all purpose gravel or mixed surface tire.
Over 500 miles so far on everything from pavement to rocky singletrack, I don't pull my punches and these tires haven't flinched. I've been using the standard GK 32's for road riding for years and thousands of miles, and no issues and no complaints. The GK+ were relatively painless to install, and they've performed flawlessly so far. They're fast and they're bulletproof. Maybe not the most supple tires in the world, but smooth enough to keep my longer mixed surface rides fairly comfortable. Highly recommended.
My use is primarily country secondary roads mixed with a little bit of gravel exploration. I use the 700c x 38mm with tubes on a Rivendell A. Homer Hilsen (57c). I find the tires to be very responsive and relatively light for the size. Running them at 50-55 psi with the tubes has worked very well for me (215 lbs.) I have ridden these tires over the fall and have had no issues at all with punctures or flats. I am very pleased with them.