I found the GKs not very grippy and also felt I had quite a few punctures on them. They were the old pre-tubeless version though, maybe the newer versions are better.
No, they were awful for me with tubes to the extent I'd say incompatible. Also grip wasn't anything special and while it may be related to my rims, a pain to fit. I have tubed G-Ones now, very pleased with them.
Thanks very much for the feedback, what makes them preferable to the GK's? - that's another tyre in the pile for consideration.
General tyre question, is there a penalty if one ends up running TLC tyres with tubes?