The new connecting rods are MUCH stronger. To date, I have not heard of any of the new rods bending. I believe it was simply a weak design on the old rods, and the new ones should last indefinitely.
I know one old mechanic who ran his German auto repair shop for decades. He's a friend of my family from way back. I asked him about the infamous 3.5L grenades. He said he'd buy one in a heartbeat if it had no symptoms, then promptly tear the engine apart and install six new/updated rods.
On an engine with no symptoms of failure. He also firmly believed the problem was the old/weak rods, and replacing them BEFORE they failed/bent was good preventive maintenance. YMMV, as usual... and for the record I still prefer the good ol' OM603.96x, 3.0L...
