I don't think there's any difference in the chargers. I think the GP chargers are lousy as they don't have delta-v. Meaning they don't actually detect if the batteries are fully charged by their voltage. They simply charge based on a timer, so the batteries get charged for 16 hrs regardless. That makes me uncomfortable cos often times I don't charge fully drained batteries and the idea of overcharging makes me uncomfortable even if it's so called trickle charge.
Furthermore it doesn't make sense as they cost the same (sometimes more) than a "smart" charger. Last I checked, I think those Sony and Energiser chargers are the dumb kind.