I own three 21's with two barrels on each gun. A 12, 16 and a 20. The 12 gets used most often of the three, the 20 when I can and the 16 almost never. The 16 is as heavy as most 12's so it is not a great gun to carry. I shoot it well but just leave it home. The 20 is my little gun when I need to impress the other Winchester snobs. A group I use to shoot with almost die when you mention that you have a 21. They think that they are the toughest guns on earth and do not mind that the gun weights a ton and a half. I am getting older and do not like tote a eight pound gun when I have soo many, a pound or better less, at home.
Buy the Fox. Shoot the Fox and never regret your choice. After your next tour over seas buy the 21 if you do not know hat to do with your money. Or better yet buy land so you will have some place to hunt.