I think that dust filter will reduce fan efficiency and increase temperature in the miner.
After all, after running miners for 2+ years, never had significant problems with dust since the fans are running high rpm.
Not using dust filter would be better for the miners in the long run.
It depends on dust amounts in the place you mine.
I was operating a SP30 in a dusty room for 4 months (it was actually a mechanical workshop, imagine the dust!)
I opened the miner and it was relatively clean. An ordinary desktop computer would of course be full of dust.
Maybe the high speed fans prevent dust accumulation.