Stuck in the middle - 50g tank, which Deltec skimmer?

[Rippin]

ok, hopefully a simple question

It's a toss up between the Deltec MCE300 or the MCE600. The size of my tank kind of falls between the 2 (seeing how manufacturers over-rate their skimmers).
The tank is empty now, but I'm planning on softies, a few small fish (maybe 5) and the typical custodians - so the bio-load will be relatively small.

It has to be a HOB skimmer that has the pump outside, as I don't want it to eat space inside the aquarium. It also has to be quiet. Now, I'm guessing that in-aquarium pumps will be quieter because the water and glass will baffle the sound, but I can't stand a whole bunch of hardware in the tank - especially as this HOB will be on the side of the tank, not the back.

So which one would you recommend?