T&T: accumulator tank

[ed]

My old jabsco accumulator tank has bit the dust. The internal bladder has 
sprung a leak and there's no way to fix it. This is the 2 gallon metal tank.
There are several variations available. Jabsco has the same tank and they 
also have a smaller tank. The big tank says 20 psi, 2 gallon; the small tank 
says 125 psi, 1 liter. The other difference is cost. The smaller one is 
almost 1/3 the price of the big one. Small one is plastic, big one is metal. 
Is there a good reason to go with the big one? 42' boat has 2 heads, shower, 
galley sink.

Thanks

Ed K