I live in Nova Scotia, similar climate I think except maybe colder/snowier winters. I currently only have 2 sleeping bags.
One is a 0 deg summer down mummy bag, that was very pricey. I'm 6 foot, and 200lbs, with broad shoulders. I normally sleep on my stomach or side, so I find this bag very restricting and rarely use it anymore.
Second is not really a bag. It's a down quilt which is not meant for cold weather. It has toggles on it, so you can do up the sides kind of like a barrel bag. I find this rarely holds through the night especially in a hammock. But it is much more comfortable. Most nights I barely need any covering anyway. However I also have a standard army style wool blanket. Back in May I did an overnight during a frost warning. I had the quilt and put the wool blanket over me tucking it under my pad to try and stop air from entering the quilt. I also wore long johns and a thermal long sleeve and a toque, but I stayed warm. It was about 0 or -2 deg C and that is the coldest I'd be comfortable sleeping in that setup.
I do need to get a warmer bag for the spring/fall/winter.