I was on Remeron when it was new and through most of grad school. I think that although it isn't known for this it had some mood stabilizing properties for me that are the sole reason I finished my master's degree. It worked for several years and then became less effective but looking back it really seemed to help contain the bipolar before it got very bad. I wouldn't take it now and expect anything of the sort but in those early days it was very helpful.

It still is one of the most effective ADs I've ever taken and I only stopped (I was off it for years around diagnosis then tried again it for a while) because it was messing with my blood pressure.

It can have weight gain as a side effect but the higher the dose the lower the risk of that. At 60 mg I had no weight gain.