Bacter AE is best used with caution, as overdosing may result in deaths... overdosing usually being at the recommended dosing amount, or even half of it. I've never actually used it myself, but as it's been explained to me, Bacter AE uses oxygen in the water column in order to grow. Using too much could result in a depletion of said oxygen in the tank, resulting in the shrimp suffocating to death. Most people who use it thus use in *very* small amounts and usually not more than once or twice a week. Not many people are able to use half or even a full dose of Bacter AE on a more frequent basis. One person even had deaths in their tank even when severely under dosing and the deaths stopped once they stopped feeding it.
In short... word of caution if you have it.
As for mineral balls.... usually more decoration than anything else... as they usually dissolve too slowly to be of any real benefit to a tank. That said, I don't know how Mineral Junkie Pearls compare to the "standard" mineral balls. Generally speaking, if your shrimp are lacking in minerals, it's usually a water parameter issue, or diet related and not something that a slow releasing item is going to fix.