I had two of the case hardened Gauchos in .357, with 4 inch barrels. These were good guns and very accurate. I gave up the cowboy stuff and sold them both. There are some places where you can buy custom grips for the guns, and I highly recommend it.
I liked shooting the .38 ammo out of the guns, since it was cheaper and I don't reload. However, many cowboy folks prefer the .45 LC since it is slightly more "authentic" and also it just feels really good to shoot the larger bore.
The choice is really yours. Do you want to be cheaper and more competetive (.38) or more authentic (.45 LC)?
Either way, the Taurus Gaucho is a good gun.
Todd