My personal recommendation, watch 1all's Pub video on tuning a Hinderer:
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I got a second hand Hinderer (a skinner) that flipped like complete crap, but I got it for really cheap and just passed it along. Then later I decided to try again and got a Fatty harpoon tanto and a non-flipper slicer. As you have experienced, non-flippers just rocket open almost like an auto, so I wasn't really worried there. However, with the Fatty I actually had whitty pick me one out, and when I got it the flipping was definitely better than the original skinner I had, however I decided to watch the above video and see if I could improve it even more, and I was definitely able to. I have since used the same process on all my Hinderers (flipper and non) and it definitely makes an improvement--but I will say that not all Hinderers are created equally, it is unfortunate but true and some just flip better than others (the two Hinderers I have left--the Fatty and a new spearpoint--are the best Hinderer flippers I have had in my hands, I would put them in contention with some of the ZT flippers). However, with that said, none of the ones I have had haven't flipped (unlike that first skinner that wouldn't really even flip with the push button method, though it may have just been an over-tightened pivot), so if you tune it using the above video, I would likely try to exchange it before making any permanent changes, as you may have just gotten one with a weak detent.
As for the sharpness, I haven't had any issues with my Hinderers not being sharp, but I have with other knives and I have read about others having sharpness issues with new Hinderers... it is really unfortunate. Not much else to say about it.
BUT, even with all of that out there and me being a Hinderer fanboy at this point, they may just not be for you, it happens. That is essentially where I am with CRK--love the looks of the knives, and I have owned a plain Seb, Insingo Seb, a carbon fiber Seb and Insingo Seb, and Inkosi, and I sold all of them (the Inkosi came closest, I really like the new Insingo Inkosi). I know CRK makes great knives, but they just aren't for me it seems (though I still want a Mnandi), and that's fine, my friend loves CRK but doesn't really have any urge to get a Hinderer (and that's with him handling my tuned and wonderfully flipping Hinderers).