I dont think any more dirt would sit on his filter than any other filter in or out of an airbox.  Yes more dirt is going to enter the airfilter can vs a stock airbox because its a larger opening and more direct.  Any dirt that does enter will sit on the bottom of the airbox canister the same way it does in the factory airbox.

Some sort of prefilter/outerware over the canister end would keep crap out of the airbox canister.