The Minelab nimh pack is overpriced by $65-70, imo. Packs of 4 rechargeable nimh batteries can be found in grocery stores nowadays for cheap!
I fly radio control planes, so knowing about batteries and charging/discharging them is essential. I have a pretty good charger that doesn't test batteries individually, but it does sense peak voltage and switches into trickle charge once the batteries are done. I'm going to solder banana plugs to a good connector to charge the Minelab pack on my charger. The wall charger supplied by Minelab is not the way to do it. If you think about it, you don't have any idea when your packs are charged, or not with the wall warts.
I saw that claim by Minelab about using only their battery packs, and it is totally bogus and dishonest. Any nimh 1.2v battery is a nimh 1.2v battery. You can bet they are using batches of whatever supplier is available when they need new batches of batteries. MIne are unmarked, generic ones.
You can go to some place like Towerhobby.com, or Horizonhobby.com and see what is available for chargers. Mine is a Hobbico Elite that does 2 independent battery packs, and each is programmable for charge rate, cutoff, etc. You can always find a buddy to solder banana jacks on to the right connector if you don't do that work yourself. Hobby magazines like Model Airplane News, or FlyRC usually has the manufacturer ads on really good chargers. That is the best way to find out quickly if charging at home is for you.
Speaking of charging rates, I don't know what the rate is for the Minelab charger. It should be 10% of the max capacity per hour. This is called C1. This is a safe rate and helps ensure long battery life. For example, a 1600 mah battery should take 16 hours to charge from being completely flat. You can charge faster and not worry so much with the nimh's. Personally, I'm going to use a C2 rate at 20% capacity. I have some 2350 mah batteries that I picked up cheap.