A few things about silicone bakeware. I have been cooking with these products for about eight years now. They work fantastically, but they do not last particularly long. After about two years of weekly use, they start to deteriorate and lose their nonstick quality. If you aren't going to use them that often, they will last longer.
The other thing is, you still definitely need to grease them, just as with any baking pan. Try not greasing them and you will see what I mean.
Since they are pretty inexpensive and can be replaced at low cost every two or thre years, I highly recommend them. But they are not miracle pans that last forever and need no greasing.