I'm not familiar with the Cambridge unit, so can't comment on how it compares in terms of sound quality to the Node 2i, but it includes a pre-amp, which you already have. You're paying for that functionality when you buy the Cambridge unit. The Node 2i is a simple device that does one thing only and has surprisingly good sound quality for the price of entry.
One of the most important things about streaming is the interface to the player. In most cases, it's an app. The BlueOS app is really good and provides access to files on your network as well as most of the streaming services, TunedIn (internet radio stations from all over the world) and Radio Paradise (a high quality internet radio channel).