I believe having a weekly limit to how much boxes you can buy per week would be better so whales don't get the best stats in a week. I definitely don't have much experience with boxes and their rates but i believe it'd be abuse-able due to the fact one million is too little in POB it'd work really well during the beginning of the open beta but once price get high again they're going to be candy.
I doubt OB prices will ever rise as high as it is in POB. The only reason the market is this effin inflated is cuz Chinese found a bug early on to duplicate Zeni