A basic gas/water separator is a simple device and they all should perform similarly. In this case I would let price drive the decision as to which one, the competitive product being a Centek unit. The "kit" looks very convenient if you aren't around any suppliers for hose and seacocks.
It will be quieter. There should be no water sounds at all, no splashing, and the additional length of the exhaust run + the 180* turn at the separator will reduce exhaust noise.
On a small boat it is sometimes difficult to find a place high enough above the waterline to mount a separator, take a look before you leap.
If you plan to spend any amount of time on the hook with the genny running, a separator is a good consideration