Charnwood Country 4 Stove Opinions Sought

Hello there,
I would love to get your perspective. I want a stove to help reduce the oil costs. The house is an old farm cottage, there is the perfect stop in the sitting room where there had been an old stanley cooker years ago.

The room is quite small with low ceilings but there is an adjoining stairway to the upper level of the cottage as well as a door to the kitchen(12ft x 15ft and Ceiling height is 6'3). As well as heating the room itself, I am hoping the heating will permeate to upstairs so I will be using the oil a bit less.

I am drawn to Charnwood Country 4 because it has a long warranty, seems like a well built quality stove and even though it's a Charnwood it doesnt cost to earth. It's output is about 4.8 KW so it shouldnt be too hot for the room it's going in based on the online calculators. They also make a slightly bigger Charnwood Country 6 that's rated at an output of 6KW but I am worried it might be too hot for the room based on the calculators. I would appreciate your thoughts. Thanks