I agree with MaxQ about a trade off. The trade off is small when taking advantage of a great meat sale.
If you have a full freezer set to -5*, whatever you toss in will freeze quickly. Heat sync principal. Like Vicki says, I don't see the value in the flash freeze setting for an item or two placed into a full freezer.
I only smoke fresh brisket. I'm trying to keep the brisket as moist as possible by avoiding whatever moisture loss MaxQ describes from the freezing process. Use a vacuum sealer where you can.