This is probably no help, but I had the leather repaired in my 400E 10 years ago on the drivers seat left bolster where it always wears. That repair is still holding, so I'll bet if they know what they are doing, the repair should hold.

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95 SL500 Smoke Silver, Parchment 64K
07 E350 4matic Station Wagon White 34K
02 E320 4Matic Silver/grey 80K
05 F150 Silver 44K