Just commuted on my fiancee's dutch-style bike in 30*C weather. I thought "It's a beautiful day. Maybe I should try her bike to have a more leisurely commute." The 16km route has rolling hills, and with the heat, the upright position, and weight of the bike, I was miserable. I was wishing I had my CX bike to move faster, or at least something lighter to offset the draggy feel of the bike. I almost feel that that sort of really upright position is only really appropriate for flatter and/or shorter commutes. Feels very inefficient and unnecessarily slow. The engine isn't super fit, but I can manage some of the same hills on the commute with a higher gear than I was spinning on her bike.

Nice to have 1.75" tires and a suspension post vs my usual 25mm Armadillo tires though!