Not many here use the tags, so I can't comment on them. Sprays can be a PITA, but you KNOW they have been exposed to it when you run 'em through.
A lot of guys around here use IGR mineral, but for it to be effective, they proper amount must be consumed, and getting consumption of dry mineral zero'd in can be a full time job, especially if there is hay to bale or mow, irrigating to do, steers to rope, women to chase, or beer to drink.
I got a half a semi load of Summer LOOMIX with IGR a couple of weeks ago, and as soon as the Doc says I can get out amongst 'em again from having my knee 'scoped the other day, I'm gonna put some out. They need to eat 3/4 of a pound for the IGR to be effective, so that won't be a problem. They will get their vitamins and trace minerals, some protein, and the patented fiber digestion along with the IGR in one fell swoop. Fresh water, salt, and adequate groceries is all that is required otherwise. One feller who used it last year weaned calves 75 pounds heavier than his neighbors, and they were all born about the same time and the pasture conditions were pretty much the same, wet and washy grass all summer long, as it rained every 3 days. I'm curious to see how it works out in these parts.