In a nutshell, I found that brisket injections weren't needed for USDA Prime and Wagyu packers. The increased amount of marbling didn't require the phosphate component to achieve a moist end result, and the underlying flavor was more than sufficient to my palate. The aftertaste from the injection powder was always detectable and I just grew to prefer the natural taste of the meat. Were I to smoke a flat or Select packer today, I'd probably opt for some kind of injection of my own making or use Cal's approach of wrapping at stall with some marinade.