I have skied a Phantom ski in really cold temp's and I felt the glide was still very good. It is a little different in different snow conditions and temp's, but as a general statement I always felt I had good glide. One good thing about Phantom is you can wax over it, as Phil suggested and it doesn't change the Phantom at all. If cold temp wax improves your glide, use it if you want to, to get an additional improvement. I personally never bothered.
In terms of base burn, I believe that wax helps with that by adding some lubrication to the ski bottom. I don't think Phantom makes things any better like wax does. It won't wear off or make it worse, but it doesn't help at all, either. You can always add wax to help with base burn. If you get base burn, the Phantom will still be working, but the increased drag from friction might be real? I put it on my skis last season and didn't have any issues with base burn, so I don't have any experience to share.
In terms of the bottom being shiny, my experience agrees with what Phil described exactly. Dull bottoms still had good glide and didn't bother me.
In terms of base burn, I believe that wax helps with that by adding some lubrication to the ski bottom. I don't think Phantom makes things any better like wax does. It won't wear off or make it worse, but it doesn't help at all, either. You can always add wax to help with base burn. If you get base burn, the Phantom will still be working, but the increased drag from friction might be real? I put it on my skis last season and didn't have any issues with base burn, so I don't have any experience to share.
In terms of the bottom being shiny, my experience agrees with what Phil described exactly. Dull bottoms still had good glide and didn't bother me.