Looking to expand my gravel grinding endurance events next year. I am wondering if an IGH would be appropriate. Particularly, I am looking at the S/A S3X 3-speed "fixed hub" and the Sram Automatix 2-speed auto-shift. I normally ride single speed, but want an extra gear for the hills. Would either of these two hubs stand up to the dirt/mud/dust of a long distance gravel grinder?