Kathleen, I took a look at the tour you'd linked and something is definitely off. The museums are now open to the public at 8:00 versus 9:00. If the meet-up time for the tour is 7:30 - that's the MEET time, not the time you actually enter - you won't be getting in an hour before the public, as stated in this text from the description.
"Just as the name suggests, people who sign up for this tour get to enter the Vatican Museums one entire hour before the general public."
To be honest, I would contact any company selling tours which promise early entrance and ask what time they actually get inside. That doesn't mean that there still isn't a benefit to having an experienced guide shepherd you to/explain some of the highlights: museums are a huge and confusing place!
Just a comment about Walks of Italy's "Pristine Sistine", which is probably the other tour you considered? Given the description, the Sistine is the very last stop in the museums before it heads off to the basilica. I'd question how uncrowded it would be by the time the tour gets there, if seeing the chapel in relative peace is the goal? This has been a very popular, highly rated tour in the past but at least one forum poster a couple of months ago - back when public entry time wasn't until 9:00 - was disappointed in how crowded the chapel was by the time the tour got there. Purchasers of that tour years back said it used to go the chapel first and then double back to other parts of the museums.
Understand that I haven't actually done any of the early entrance tours recently, and not since the Vatican changed the public entry hours last month and removed their own early entrance products off their website. Just trying to keep a finger on what's shakin' with the most-visited attractions in Rome; the only constant is change, eh?
