Rush - Progressive Rock?

Well, everyone should know by now I'm a big Rush fan (my nickname has nothing to do with the recently released movie, and everything with the legendary trio from Toronto), though if you look at my reviews you'll see I'm perfectly capable of being objective.
 
However, I'd like to say just one thing to those who doubt Rush's progressiveness - are latter-day Porcupine Tree (a great band, and one I enjoy quite a lot), in spite of their longer tracks, so much proggier than Rush in terms of song structure? Do the fantasy-or sci-fi-related lyrical content or the length of the songs really make a band prog, rather than the approach to composition and the ability to reinvent themselves, to incorporate diverse influences into their music and reinterpret them, to never play it safe?

Rush took a big risk with "Vapor Trails", and I think they should be respected for that - much more than those bands who don't seem to be able to do anything but endlessly reproduce their one successful album, or even imitate music that was authentically progressive 30 years ago. Waiting for Rush to release "Hemispheres #2" is, in my humble opinion, not only unrealistic, but not very flattering to the band and their unique outlook on music.

Sasquamo wrote: If I progress my musical style from pop to punk does that make me progressive rock?

If Rush isn't prog, exactly what is it? Surely you can't say they are mainstream or Pop/Rock just because of Vapor Trails? Look at Snakes and Arrows, it's not that mainstream considering it has 3 instrumentals, and songs like spindrift. Rush is a strange breed, but we love em that way. Don't sell them short by taking them out of a category they've worked hard to put themselves in.