LeeH,
This is a very basic system and with an amp like the Onkyo 308 (the cheapest in the range) providing the muscle, it will be inadeqate for a mid-sized or large room, in my view.
Having said that, it should suffice for a small room. I'm unfamiliar with your Bose system so cannot provide an input as to the sound quality of your present system compared to the Onkyo.
Ronald