I'm only passing on what the owner who works on only MB's said and changes many of them I'm sure.
You can use any OE replacement part you want be it Febi etc. Its your engine not mine. If it last 100,000 miles or more fine, if it doesn't so be it.
I was only telling you what a MB shop passed on to me in conversation. I do know he had some problems with the tensioners other than original equipment. To what extent I don't know.
1989 420SEL 105575 miles
1990 Chevrolet E-Cab C-1500
1989 Olds Toranado Trofeo'