I just joined the Opinel club Friday. Did my internet research, and decided a No. 6 was for me. Stopped in at a local hardware store, and they had a box display. Most of the knives had been sold, but they had one No. 6 left, plus a few 8's and 9's. I picked up the 6, then put it down to try an 8. My wife picked up the 6, put it in her pocket, and said, "I'm taking this one!" The 8 seemed a little large, but I bought it anyway. After carrying the 8 for three days, it doesn't seem too large in the pocket. Either the light weight, or the handle shape with the wide end keep it in a comfortable spot. If I go back and find a 7 in stock, I might go for it, but the 8 seems fine.
Just for completeness, I do have large hands. I'm 71, so I use a knife less hard than I used to, mostly for food prep and box opening. Where we camp, fires are often restricted, so I don't do as much campfire knife work as I used to. Don't know how the Opinel would be for heavy use. My previous carry was a Case mini-copperlock, for about 10 years. Before that a Case trapper. Even though the Opinel 8 is 1/4 inch lager that the Case trapper, it carries easier in my pocket.