I have a few lifters making noise until well warmed up

The need for ZDDP really depends on the cams rate of lift (intensity, if you will) and the valve spring pressure. If your running a stock or lazy grind cam with low spring pressures it may not be needed. But for a cam like yours I can't say I agree with only needing it for break in if your running the springs it calls for. I figure it's cheap insurance