Whole wheat panko is interchangeable with regular panko, right?
I bought a bag of whole wheat panko because they were out of the regular stuff. it's browner, but everything I've made with it (meatballs, fried fish) turned out pretty much the same. Safe to say they're interchangeable?
Interchangeable, yes. But you are wasting money using panko in meatballs. Panko is specially made to result in extra-crisp coating of fried and oven-fried foods. You're paying extra for that property. For the panade in meatballs and meatloaf, where bread crumbs are soaked, use up whatever stale bread or crackers or unsweetened cold cereal you have on hand.