These are great tires in my opinion. I have them in a larger size 35x622. On my road bike with i21 rim width they were true to size. On my gravel bike with i23 rim width they stretched to 37. Both bikes are disc and brake clearance wasn’t an issue for me so, I can’t really speak to that.
Thanks for your comment, appreciated. Good to hear that the tires are mostly true to size which is what I heard from a friend too (even though conclusion was that with the rims never know 100% exactly and might just give it a try to find out). Still thinking a bit.
If you plan on riding gravel at all, I would go with the gravelking SK vs. the GK slick. I used the slicks in 28 mm as a pure road tire and found them to be quite fragile. The sk however is great, very flat resistant and reasonably fast on pavement (I ran 32s on a different bike with more clearance though).
I was able to fit the 28 gk slicks with a DT 460 rim Into Shimano 5800 calipers without maxing out the clearance.
My absolute favorite is the good old Panaracer Pasela. They are cheap, light and have very supple sidewalls while the tread area is well protected against cuts. And they look classy too imo.