I don't know enough materials engineering to know if there is an advantage to using nickle over chrome. I've always been under the impression that the guys who really KNOW engines prefer chrome and think the use of nickle is more of a cost savings thing than a real improvement in engine design. As I understand it, chrome is harder than nickle, and therefore wears better. However, like I said, I really don't know for sure, I could be way off here. I've never heard someone from OS (or otherwise "in the know") explain why they use nickle while everyone else uses chrome. It's a mystery. But the good news is that it really doesn't seem to matter in actual use. I happen to like OS engines, though I think they are bit over-priced.