I was also going to post this bit with my first post, but I didn't want to assume you were thinking/told that thinner tires means faster.

To be honest, just forget about that and do ride the sirrus. While it might be true that you can get 'faster' on thinner tires because of roll resistance or whatever, you said you are new to cycling so your legs need to really be built up to notice any significant difference. If you are riding on the stock all condition sports tires, that is the same brand of tires on the allez, with the exception of thinner width. They aren't bad tires and I am sure there are better ones but it comes down to money again. Personally I am a cheapo so I'd ride those stock tires down first, then switch to something else more road oriented.