Path,
I have a blue five inch, and a blue six inch (thin barrel versions), and have been looking for a four inch blue, thin barrel 10-5 in pristine condition, for several years now (without success).
Some day, I hope to own a blue thin barrel 10-5 in every barrel length.
Since there were so many model 10 variants, I can't afford to collect them all, so I limit my choices to that finish, engineering change, and barrel style. I also like the wider front sight on the 10-5, so that was a consideration.
Both are a joy to shoot, but the six is my favorite.
Bill