Is a stall completely necessary, or can your horses make do with a run-in shed? What types of things did you (or would you) take into consideration when choosing between a barn and a run-in?
Most horses I have found can live quite well with just a rin in shed. However Stalls have their advantages such as. you have more hands on time with the horse when you turn them out, this gives you a handle on their condition or any developing medical issues.
Yes, I agree. Usually if people are unsure, I like to point out that you can usually affix pipe gates to a run-in to make a "stall" that you can keep a horse enclosed when needed.
The main reason I prefer stalls overall is that you can shut a horse in if they are hurt or something.
I like a combination of both run-in for daily living and stalls for as Nicole mentioned if you have to isolate them. From what I have read and talking to Vets, run-ins are much healthier, less chance of repertory problems form dust. I think that would depend on how often or how long the horse is stalled and how clean the barn is kept.