I sent 2 hunters to them (ATS34) heat treated and cryo treated. They turned out very good, better than any production knives I have used in ATS34. They were also prompt, and had the blades returned to me exactly when they said they would.
Folders shouldn't be any different other than pricing. If you go to their website its all laid out, there is an additional charge for folder peices besides the blade. Not an issue if your making linerlocks and use Ti, or can heat treat the liner yourself.
I use O1 now and do my own HT. Saves alot of money, and I'm starting to like O1 blades. If I do any stainless I'll be sending it to TKS though (unless I was doing enough to send an order to Paul Bos, his pricing is different), I've been real happy with all my business with them.