Gents:
Recoil should not be a factor if the rifle's weight is proper. Using math calculations for felt recoil, a .600 at 15.5 pounds will feel the same as a .577 at 12 pounds and the same as a .500 at 10.5 pounds. Approximately, of course, and I know there are many factors as stock dimensions, etc. But, generally speaking, rifle weight make up most of the calculation.

The A-W rifles are very nicely done and will have a page in my new book on double rifles. The side lock rifle is priced higher as I believe it is English made where the box lock is made using a French Verney-Caron action and maybe barrels. V-C are fine rifles but cost far less to produce than a London made double rifle.

.577 vs. .600. I've owned both and still have my .600 Wilkes (sold the Jeffery). They are cool and have a great "wow" factor, but I doubt anything over the .450-.470 class is really needed for big game. That said, it's not what you need, but what you want. That is why I shoot the big rifles often but hunt with a .450-400.

Cheers, gents.
Cal