Without having the book in front of me to actually see what's going on....this APPEARS to be a brine mix:
"Myron Mixon's marinade recipe -- 3 cups apple juice; 1 cup distilled white vinegar; 3/4 cup sugar; 3/4 cup kosher salt."
in which case it's designed to work chemically a certain way.........equal Kosher salt / sugar draws the flavoring all thru the piece, so it would be a good idea to not vary.....
Also, if you do this do not sub regular salt for Kosher as the different grain size doesn't translate straight across....i.e. 1 cup of one does not equal one of the other......
Myron also pumps whole hog full of 5 gallons of apple juice or something, so he''s aiming for a sweet, with slightly tart aftertaste pork........that is what you'd most likely get from a mix like that brined say, for 8 ~ 12 hours (?)
The vinegar will do more toward tenderizing than actual taste, I believe............
The above will be generally true, if it's supposed to soak, submerged for a length of time....below is some experimenting I did with injections:
http://weberkettleclub.com/forums/grilling-bbqing/re-print-ok-what's-in-kettle-3/msg35831/#msg35831see at the end for mixes; the rubs were dissolved in the juices, then shot all thru the pieces......sorta changes things, but not a huge difference as injections tend to "migrate" either toward the heat of the outer edge of the piece or toward the center by the bone.......it still works decent, as it's all pulled & mixed in together at the end & the flavoring mixes up......
A brine like what that looks like will work thru the whole piece better anyway so try it out if you'd like....
Personal opinion is just rub the outside of a decent size (8~10#) butt & let the fat render correctly & have it taste like the porky goodness it is........
Have sauces to add if people would like......this is a great one from MacEggs buddy Roxy up north:
Mustard Vinegar Sauce
1 cup apple cider vinegar
1/2 cup Yellow mustard
1/4 cup onion finely minced
2 cloves garlic pureed
1/2 teaspoon black pepper
1 tablespoon Worcestershire sauce
1/2 cup brown sugar
1/4 teaspoon cayenne pepper
1/2 teaspoon salt
1/2 teaspoon Tabasco sauce
Combine ingredients and simmer for 15 minutes, stirring occasionally.
For a smoother sauce, blend on high for a few minutes.
I bid you a great cookup !!!!!