Just submitting my notes as there's not a ton of info on Phantom Glide (PG) I've found from a practical perspective. Disclosure that I haven't had a chance to use my treated skis yet and I'm the test for my group. Many of my more technical ski friends hadn't really heard of PG until I brought it up.
Ski Town by far has some of the best pricing for PG application and their shop is open all year. Their techs and owner are very knowledgeable, friendly, and I can't recommend them highly enough. Their tech has run PG on his own skis for a couple of years and recommends it.
My situation: I just bought a new set of Armada Whitewalker (116mm) powder skis after using a set at Niseko and loving them. Realistically I don't get many powder days that warrant pulling them out and found about about PG as I was doing some research. None of my friends had heard of it but seemed like a good thing as 1) I wouldn't be waxing these skis often and 2) I hate sticky skis. While you don't need a lot of wax for for powder, there's a lot of groomers and traversing that's usually involved at the resorts (I'm not backcountry).
Still seemed like a big investment without a lot of evidence that it works.
Notes: Was encouraged that DPS (high end skis) applies it by default to all their skis. However according to Google they own PG so some bias there, but doubt they'd do something to mess up their skis. Heard that Aspen has applied PG to their rental ski stock this year, which really makes sense if it does what it says and also eliminates having to wax. Points for being environmentally friendly too.
Anecdotally PG works fine for 80% of the conditions (except the hottest and coldest), and is definitely an improvement over not waxing over a few days. You can apply wax over it without issue if you're looking for peak performance. I'm looking forward to testing these skis out with PG and will try to remember to provide an update in a season or two.