If I was going to get an SP101 to concealed carry I would want the 3" barrel for ease of concealment. Smaller grip, smaller cylinder, shorter barrel.
If I wanted a gun to go out and shoot, keep by the bedside, or open carry around the property I would go with the 4" GP100. Replace front with with a tritium night sights.
If I wanted the capacity of the GP100 but a 3" barrel, ruger offers one in that size. It is not going to be as concealable because the larger cylinder and grip.