As far as 50 round hoppers go that's the best but you'll want 50 round pods to go with it, nowt wrong with a viewloader 200 shot basic one for pump, or a primo, then you can use your existing pods and pack. I tend to use a revvy or an old site 150 round hopper on my cocker pumps since the marker is quite big anyway.
depends if you are fussed about getting a fast rate of fire but that will no doubt depend on what kind of marker you are using. i'm no pump expert but i notice if i try to go for a fast pump stroke that i'll chop, double feed etc if i don't use a force feed loader
Another vote for Primo here. Costs peanuts, small profile, zero batteries, 200 shot capacity and feeds great on all my pumps. It even works well on electro's...
Ignore the first 50 seconds of bollox but rest of video is ok