The DNA filters flow more air than foam, as all cotton gauze filters do. Power/torque will be greater. However, as you rightly suggest, the foam option is the better bet in dusty conditions.

A lot of people use the OTR foam filter, it is apparently better than the Pipercross (which has been known to fall apart).

Another advantage of foam is you can keep a spare, pre-oiled element squeezed into a ziplock bag ready for a quick change in the field. Carrying a spare DNA filter wouldn't be practical, being a lot heavier and taking up more room.

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