Dear Dylan,

Please don't take the conclusions before overall assumption complete:
Assume we have:

1. Two simple "DIFFERENT" models. So this not talking about the model stay the same like Omdo said but compasrison two diferent models.
2. Model I takes SAL and Model II takes SA as their allowable.
3. The both models have "SAME" stress ratio in many nodes case EXP.

Model II which using SA will have better flexibility insteaf of model I using SAL as allowable (assumtion no. 3 shall be fulfill at first). But model II may will need more pipe in order to make its ratio let say the same with model I.

When I said that Model II better in flexibility and will have more longer fatigue life is only my own opinion. My opinion based on that fatigue is failure mechanism in EXP case.

I also agree with Omdo:
better flexibility is less conservative approach/calculation when using SAL formula instead of SA one.

I think I mean the same by making comparison of the two models.