Always dangerous to assume, but I read it that you only do a base grind when it is needed as normal, not to recondition the Phantom treatment. DPS says that a base grind does not get rid of the Phantom treatment because the Phantom permeates the material thus a base grind does not eliminate the Phantom.
My take is a Phantom treatment is good for the life of the ski.
I did not feel like it was as slippery in the lift line as a freshly waxed ski, but was very good while trying not to fall (i.e. while skiing)
"you only do a base grind when it is needed as normal" The question is...what is normal?
With good waxing base care, a base may go for a super long time before a grind is "needed". I fact, it may be at it's peak speed after all that skiing.
Then you can get a new ski that needs a grind for structure right out of the gate.
Then you can get a new ski (or have one ground) that is so deeply ground that it needs steel scraping right out of the gate to speed it up.
So when it comes to stone grinding a ski, there are too many variables to say there is a "normal"