Many reasons why people de-assist, or avoid assists altogether.
With good design and engineering, a folder, even a flipper, doesn't need an assist to open reliably. An assist is often used to compensate for poor design.
Assists add complexity to the design, and, especially in the case of the Speedsafe, a weak point. This is not speculation, they do fail reliably.
Many people, myself included, find the "resisted closing" feature to make the knife less safe to use.
Anecdote: I asked to see a Kershaw flipper at the Big5. I don't remember which model, Blitzshock maybe. It was drastically discounted, and I liked the overall shape.
I inspected it, found the centering was way off, and asked to see another. The man handed me another in box, I handed him back the closed knife I had inspected.
He wanted to check it out, opened it up, and upon attempting to close it...
Sliced the hell out of the middle of his left palm. Badly, lots of blood.
Somewhat freaked out, I just grabbed the unopened box and purchased it, while his colleagues attempted to stanch the wound.
I should have just left, as I ended up hating everything about that knife.
This model had no detent, so would not de-assist. Reassisted it, left it alone, never carried it.
Pulled it out one day, the torsion bar had failed. Yes, even by not using the knife, it can fail, because the bar is under tension when the knife is closed.
Some suggest you store your assisted knives in the open position. No thanks.
I kept it around to remind myself why I don't buy Speedsafes, until I cannibalized it for the washers and tossed it.
So it's basically a no-go for me, as it doesn't confer any advantages that can't be achieved otherwise.
Which is too bad, as my aversion to assists basically disqualifies every knife Kershaw has made for the past several tears.
I really like the looks of the Link, but I don't know if it will function de-assisted, so I haven't bought one.
Now if they re-released the Chill, on bearings, in Sandvik, with a wider choil, Kershaw would be back in my good graces.
*One "assist" I did like was the In-draft system on the HK Enigma, now discontinued.
Also seen on the Benchmade Ambush, In-draft is a feature only apparently used in conjunction with the uncommon Rolling lock.
It was actually more of a closed-bias mechanism, but did provide a gentle push when opening the knife.
Enigma was one of my favorite folders, until the In-draft broke. Could not be repaired or replaced, sadly.
