I have a Scott SUB 30, and also bought it secondhand with the 26" option. I've never had a problem. Thinner 26" tires are widely available online, many as thin as 1.0, around 90-110psi. For commuting I don't think you'll see a difference, I know I don't.
and don't get carbon anything. buy some nice accessories now, then wait a bit and get a new ride. I'm currently looking at stuff to build a fixie or SS.