I've been beating my head against the wall trying to make a decision about sashing or not. I was on the fence; my friends were definitely for it. I went ahead with a skinny one...only 0.75 inches finished. I like that the eye has somewhere to rest, but it seems so stark...needs borders, I guess.
When I put the blocks on my design wall without sashing, I felt a little overwhelmed with how busy it felt. I think I need to sleep on it...