I used the FHF compact (slightly smaller than the small) harness/rf pouch last weekend at TAC in Utah - and it fit my 10x42 Vortex Razors like a glove. Leupold fulldraw 3 rf in the pouch. I'm not sure what I was more impressed with over the weekend, the Crispi Thors or the FHF Harness. I put about 30 miles in the mountains with the FHF on the entire time and it performed better than I could've expected.
The fhf harness comes with standard 1" clips. I did change out the left side male buckle to a AGC 1" locking buckle to prevent any slipping. The rf pouch disables the right buckle (or left, depending on which side you mount it) because of how it attaches to the harness and theres not enough space to mount a locking buckle on that side, so I replaced the male buckle with an ITW waveloc on the right side. I have no idea if the standard buckles would've slipped, but Ive had issues with them before and went ahead and changed them out. Over the 30 miles I hiked in the mountains on the shoot, I didn't have to retighten the harness once. I do like my bino harness to fit snug, so I was pleased with the performance.
All that being said, I do own a AGC Hybrid harness. My only complaint was that it was on the bulky side but I never really had an issue with it. Its still a damn good harness. But I decided to give the FHF a shot because on how streamlined it looked, and I wont be going back to the AGC.
I would say that if you like your harness to fit loose and not snugged up too tightly, the AGC might be the way to go. If you like the harness tighter and more secured with less bulk out front, then its the FHF. Both really well designed harnesses, but for me the FHF is perfect.
Good Luck with whatever you decide to go with.