Gearing ratios will be more important for riding up hills than weight in my opinion (unless you're comparing your bike to a 45 pound Dutch style bike or something). My first recent bike was a 2011 Trek 7.3 FX WSD 19" with a triple up front and it's aluminum. I recently bought a 2011 52 Surly Cross Check with a compact double which is steel (Chro-moly), and it feels lighter than the aluminum Trek. As I considered various bike models I made gear ratio graph to compare. I wanted to be able to climb hills at least as easily as I was able to on my Trek. With my steel bike I lost my two easiest gears however I never used those anyway so it didn't matter. The steel of today is not as heavy as the steel used 30 years ago. Given that I would be more focused on the gearing. The Salsa website will tell you how many teeth are on the chainrings and sprockets on the rear cassette and Sheldon Brown has a gear ratio converter on his site. Or just go test ride a Casseroll and shift to the easiest gears and ride up a hill. That will tell you soon enough.