I've shied away from the shale interior for just the reasons you describe. It looks great when new, but after several years . . . Black gets hot without a sunscreen, but both the ebony interiors and suede inserts of my cars look new.
You might want to drive the car over to a dry cleaning pro and have them check out the suede insert prior to removing it from the seat.
Try applying some isopropyl alchohol with a nylon brush on the waterfall behind the seat. Follow up with some decent plastic dressing --not Armorall. Find out where the back of the seat is contacting the waterfall and place some Kapton or other non-sticky, teflon-tape take there to minimize abrasions that lead to scuff marks. (Don't try for the quick fix and use duct tape; it leaves a nasty adhesive residue and looks bad anyway.) I used Kapton under my hood in an area where the paint was being abraded due to vibration with a plastic surface and it worked great. I replace the tape once a year due to the engine heat which eventually loosens the adhesive.
You can always opt to replace the worn insert too.
CC :seeya
