Why? and does this mean I should be opting for 6 bolt?
Because 6-bolt has been around for longer, and is cheaper to manufacture. Novatec sell mainly to very price sensitive OEMs.
You should be opting for 6-bolt, but not for that reason. The Center Lock spline is designed for light weight and ease of assembly/disassembly, and as a result it's badly designed for torque transmission. It sacrifices durability on the altar of light weight. This is fine if you think that's a good trade off, but for most people it isn't. If you designed a spline connection to be as strong and durable as 6-bolt, it would be heavier as well as more expensive. That's why brake rotors, with very few exceptions*, on every other kind of vehicle are attached with a circular pattern of small bolts.
*Multi-disc brakes typically found on large aircraft and as industrial machinery brakes are spline driven, as the rotors and stators need to slide laterally on the hub and axle respectively in the case of a wheel brake, or the shaft and housing in the case of a machinery brake.
Because 6-bolt has been around for longer, and is cheaper to manufacture. Novatec sell mainly to very price sensitive OEMs.
You should be opting for 6-bolt, but not for that reason. The Center Lock spline is designed for light weight and ease of assembly/disassembly, and as a result it's badly designed for torque transmission. It sacrifices durability on the altar of light weight. This is fine if you think that's a good trade off, but for most people it isn't. If you designed a spline connection to be as strong and durable as 6-bolt, it would be heavier as well as more expensive. That's why brake rotors, with very few exceptions*, on every other kind of vehicle are attached with a circular pattern of small bolts.
*Multi-disc brakes typically found on large aircraft and as industrial machinery brakes are spline driven, as the rotors and stators need to slide laterally on the hub and axle respectively in the case of a wheel brake, or the shaft and housing in the case of a machinery brake.