Looks like a nice upgrade. The best upgrade I made for my Dahon 20" folder was a 2X crank and derailleur to get additional lower gearing.

I've shied away from carbon, a LBS has a web page devoted to fragility and bad failure modes of it, they only endorse its use for competitive racing bikes, and they won't service a lot of it. It also requires very careful installation to keep from damage due to clamp loads, such as using friction paste so you don't need to clamp as hard.