IMO if you aren't a track junky, there's little to gain by changing to hardened bolts.
The issue is strictly one of improper torque at the factory.
AFAIK, there haven't been any broken bolts.
I properly torqued mine; no nordlocks; no loctite and have been running several years w/o issue. (I put a dab of paint on the head so that I could tell if they were backing out)
This whole issue has gained a life of its own that far exceeds the real issue. ....again JMO.
If replacing, there are two different lengths.
If you look them up on real OEM, it lists the bolt length and size.