i have a 560 blackwash and the detent was too strong when I first got it to be able to open via thumbstud. However, after a ton of flipping and carrying, things have settled in nicely.
I have a 566 which has the perfect detent I think, but I've also deassisted the knife, so the action is certainly different than stock.
I have 2 550's, both gen 2s, and the one with the black blade has a far stronger detent, but not to the point of being uncomfortable after breaking in.
I have to say that all these knives, with the 566 being the exception, took some time to break in and have the action settle down to make things comfortable. The 560BW is easily the smoothest, best opening flipper I have ever owned...