I love foam filters. I don’t mind washing and changing them as I have to do my race bike and my sons. However on the AT getting to the filters is a 15 min job to take of both fairings and getting to airbox, IF you get the hang of it.
My bike is just shy of 8000 km.
Of that 2800 km was 2017 Quest and bootcamp.
And then around 1000 km Tankwa and commuter and the last 4000 km was our trip in Namibia that was in harsh conditions.
I checked the filters in Purros during Quest, then before our trip and this morning after our trip.
I would not go away from the standard pre oiled fabric filters. They are amazing. Not to sound snotty, but you will be hard pressed to find a AT that has done more tweespoor and rough tracks than dirt and tar in relation to its total odo kilometers.

The filters are super dirty now.

However the airbox is spotless

Insides of filters are spotless

Just for interest I banged the filters to see what came out of them. I blew them out with a airline and they are OKish to use if I had too, but after 8000 km I will rather replace them.

Not even Fesh Fesh made this filter have problems.
As far as possible I always try not to ride in unnecessary dust of people infront of me, but for the rest I gave her stick.