My commute was only about 6 miles each way, but I am also choosing to use my Bike Friday 'Pocket Rocket' (very similar to the NWT) for a 70 miles/day camping tour to Yosemite starting Sunday as an indication that I have no issues using it for longer rides (and it's been on many century+ rides). Mine and the NWT both have chromoly steel frames and use pretty standard components. Mine uses a regular Shimano 105 double crank with larger rings (60/42) to compensate for the smaller wheels, but many are equipped with the Dual-drive rear hub using a 3-speed internal gear plus a regular cassette and a single front ring. The NWT on CL has a more normal double chainring and gives proper gearing by using the Capreo cassette that has a 9-tooth smallest cog - works well but limits you to that cassette.

Note that the NWT is primarily designed as a travel bike rather than a multi-mode commuter. I.e. emphasis is on still being good for riding on longer trips but at some sacrifice in ease, compactness, and time to fold it. So don't expect it to fold as easily and compactly as a Brompton (or Bike Friday Tikit), but it should be well suited for your longer ride. And many transit systems just have a requirement that the bike be a 'folder' without specifying a compact folded size.

Note that the NWT (and Pocket Rocket) are customized somewhat to the original buyer - you send them measurements from your current bike that's been properly fit adjusted and they build the frame so you'll be in the same position on the Bike Friday. So if you buy used you may want to check that your body size and proportions are similar to those of the original owner.