Timing chain advice, split roller or solid

When Rollmaster first appeared, they used hard steel for the sprockets. Hard steel, not hardened.....
There is a difference. The hard steel was easy to machine, but the teeth wore quickly. I have early sets here with less than 10,000m on them & you can clearly see the teeth developing a hook from wear. After JP bought RM, they are using hardened steel which doesn't wear as fast. I like c/iron for the cam spkt, excellent wear properties.