My first SYK was the SS4 and the thing that convinced me to buy a knife that was more expensive than any other one I had owned was if I did not like it I could sell it and get my money back. Well I was so impressed I kept it and I have bought a DF and a M6 as well. I would have prefered the S6 to the M6 but it was even cheaper than an S6 was new and came with one of Leatherdogs sheath.