Not too sure about Barretta, but Stoeger, Cimarron, and Uberti are all the same, made by Uberti, who is owned by Barretta. So, as far as choosing is concerned, take you pick for what suits you best.
As to +P in the little Stallion, I wouldn't recommend it. It won't blow up in your face, but it sure batters the gun.
If you want .357 Magnum strength, stick with the larger frame, which is still pretty handy in size.
And one of the advantages of +P is that you get near-Magnum performance with a shorter case for easier extraction