Performance - Less flow rate, not a higher WOB (not that I think WOB is all that great an indicator of anything anyway.)
50's first stage versus Legend first stage - It's a matter of detail and degree. Technically all diaphragm first stages function the same, it's the differences in internal volumes, porting etc, that make a difference in flow rate. The Legend has a lot more in common performance wise with the ATX200's first stage.
It's also not that the ATX 50 is not up to the task, it's an issue of getting a lot more for your money with the Legend LX if you can get it for the same price as an ATX 50.
50's first stage versus Legend first stage - It's a matter of detail and degree. Technically all diaphragm first stages function the same, it's the differences in internal volumes, porting etc, that make a difference in flow rate. The Legend has a lot more in common performance wise with the ATX200's first stage.
It's also not that the ATX 50 is not up to the task, it's an issue of getting a lot more for your money with the Legend LX if you can get it for the same price as an ATX 50.