I have the Ruger SP-101 and really like it, although it is a little heavy for such a small gun. This however is an advantage when you are shooting a .357. I have fired over 100 full house .357s out of my '101 in one session and didn't think it was bad at all. There are some practical decisons to make with a gun like this. If you are carrying it, you want something as light as possible. But when you are shooting real .357s out of it, you want it to be as heavy as possible. You have to decide where your priorities lie. A gun is no good to you if it is lying at home (because it is too heavy to comfortably carry), it is also no good to you if you can't hit anything with it (because it is too painful to practice with). Which ever way you go, the .357 is tops for a defensive caliber.
Just to beat a dead horse some more, let's look at the .38 vs. .357 one more time. If a .357 produces more velocity than a .38 in an 8" barrel and in a 6" barrel and in a 4" barrel, why would this sudden go away on a shorter barrel ?