I was introducing someone tonight to Geocaching. I hadn't played in a while, but I clicked that premium button, as I knew I was about to start again for a while. We started walking to get to caches, and half the time, she was disheartened that the cache was a grey one. Since I wasn't up to date on the particular restrictions, I couldn't quickly explain what was happening.
It made for a really weird experience. She still liked it, but those advanced caches that are blocked are a seriously bad idea.
If it is to protect new players, make it a toggle or something. If it's to make more money..that's not the way to go.