Yes, the Dillon 650 is a fine machine.
Doing 147gr at moment, so can't help with the data, but like all ammo, some run better in differnt guns and I start low on the chart as well. Unfortunately it takes some time to do small batches and test just becuase of a time thing, so I did like you and ran off 20-30 rounds and they were decent, so did not really change anything except playing with OAL.
With the lighter load my Caracal would sometimes not lock back on last round, but otherwise was fine. I would see no problem in increasing to 4.0