I hate to dredge this thread up from the dead, but...
Let me preface by saying that I'm pretty new to knives, so excuse any mistakes I made. I was at a store yesterday and looked at a 670. The one on display had the optimisor disabled, and the salesman pulled one out of stock for me to look at, to see what a 670 with the optimisor was like. I found it to be very stiff at first, and required a lot of force, but when it hit the opening point it flipped very fast. In other words, I put a lot of force into opening the knife, and when it did open, the blade outran my thumb. Problem was, my thumb caught up.
Go superglue. My thumb's out of commission for a week, the cut was about 1.5 cm on the right side of my right thumb, so no pistolero-ing for a while.
Otherwise, the knife seems pretty nice. Don't much care for liner locks, but it is a nice looking knife. I'd disable the optimisor though. I'm a believer in the factory edge.