well, the thing i don't like about the box setup is an issue that we ran into on combines, they don't actually seal to that plate, so chaff builds up, and if you need to change a filter in the field, but have no air, there is a chance of contamination. luckily though, we run gleaners, so there is still the spin-on filter at the motor to filter chaff, but i am still not a huge fan of the cleanliness of this setup.
And, by the above reference to the combines, I am wondering if the box is that good, why did gleaner go from tank to sediment bowl to box setup to the newer setup of tank to box to spin-on? Im thinking there was a good reason. I have still not found anything on the micron size on a box filter either.