I have a Hack 1 and its great. Not ridden any CX on it but its a great commute bike and i did the Etap yr Eryi mawr on it recently without too much fuss. I reckon if oyu put some knobbly tires on it it would make a great effort at CX or gravel bike or whatever you want to call it!
I got it to make my commute a bit easier and it definately worked. i did put a 11-30 cassette on the back as have a few killer hill to negotiate! I also changed the original brakes to BB7s and it made a good difference.
I cannot recommend them enough.