They are two completely different bikes. If you really plan on forest paths, you don't want the Sirrus. If you want to go faster easier, the Sirrus is the bike for you.

I have both, albeit, older, and they both excel at what they are best at.

The Crosstrail is a great do it all bike, a great commuter, and a wonderful utility bike, that likes to go fast. It is comfortable, easy to ride, very stabile, and looks great. Capable of gravel and dirt paths, as well as good on pavement.

The Sirrus is a great commuter, really likes to go fast easier, light, comfortable to ride, doesn't ride as soft as the Crosstrail, but more twitchy in handling. Not quite as stabile, just different. Easy to ride fast. Likes pavement, and capable of packed gravel.

They are both great at what they are good at.