I've always had my buns in for winter and out for summer, so they are technically neither, or both, depends how you see it!
I guess thats pretty unusual, but i think its the best of both worlds for them. They get to be warm and dry and get loads of exercise in the winter, when if outside they would be huddled up in their bed all day, but in the summer they get maximum time of warmth and sunlight and good grass!
I guess its expensive to have both set-ups, and you have to adapt them each season, but it doesnt take much and they are still very responsive to me and spend time inside in the summer in the evenings etc anyway.
If your buns go outside and really bomb around and will spend hours mowing the grass, they may well appreciate being outdoor buns, especially if they are not that friendly with you,