REKAT's Quality Control is a "work-in-progress" as is the case with many cutlery companies. They appear to me to be taking the bull by the horns in this respect and are improving their product line's performance.
On their latest models, the Sifu in particular, QC has come up considerably. Mine has an action that is nothing short of outstanding. It flies open with a flick of the wrist and locks up tight every time. There is no blade play in any direction and the knife feels Solid. The heat treat on the ATS-34 blades are some of the best I've encountered to date.
I admit that my Carnivour, which I bought last year, was gritty in the action. I took it apart and polished up the inside of the liners and the blade at the pivot area and removed some gunk from the Rolling Lock mechanism and re-assembled it and it performs like a dream now.
The Carny now performs like my Sifu does out-of-the-box.
I would recommend that if you have doubts, go to your local cutlery dealer and handle a couple of REKAT's product and judge for yourself whether it meets your criteria. For sheer brute strength, one would be hard pressed to top REKAT's product line.
BTW, if you live in a state that is not Draconian in their knife law's blade length limits, by all means check out a Sifu.
They absolutely RULE!
------------------
The individualist without strategy who takes opponents lightly will inevitably become the captive of others.
Sun Tzu