I have all of these knives. As a matter of fact I started with the 6 and then got a 7/7 and then got my 4.1 and the 5.1 on the same day. The difference between the 6 and 7/7 comes down to the choils. The 6 and 7/7 edge length are the same size . Next choice do you want a (larger) small knife or a med knife? The 5.1 can do 85% to 90% of what a 4.1 can do. Again it's a matter of preference. I prefer the 5.1 and the 7/7 because I like choils and med size knives. I work with very hard, treated and med size wood. For this medium I need power and control. If I were working with soft, green and smaller wood I would work with the 4.1. The 6 or 7/7 paired with a 4.1 is a great combination. OR the 5.1 by itself is a great single carry knife. There's no bad choices here, it all comes down to how much do you want to spend. But, again, do you like choils? If so you might want to keep the 7/7 and sell or shelve the 6 or vice versa. Same with the 5.1 v the 4.1 size and choil v no choil. Of the 4 knives mentioned I really only use my 5.1 on a regular basis. My 7/7 is my camping and batoning knife, my 4.1 is a back up to my 5 and my 6 is my 7/7 backup. Confused yet?
