If I recall from when I bought a synapse for my wife, the women's models have about a 1-1.5cm shorter top tube, which would be beneficial for somebody with proportionately short arms.
The saddle is usually a women's saddle but since most people ditch the stock saddle anyway, that shouldn't be a problem.
You say you felt cramped on the 48... my guess is you had the saddle too low anyway, which will contribute to the cramped feeling.