As so many others have noted, the 4 inch model is a superior choice for all around use.

I have 3 S&W revolvers, a 4 inch 67-1, a 4 inch 620, and a 6 1/2 inch 610. What I have found is that the more weight in the barrel, the more difficult it is to shoot accurately in rapid fire double action. Back when I could afford to practice weekly, with my 67-1 I could shoot a 3 inch group at 40 feet with a 1/2 second interval time. With the 620 the best I could manage using the same 38 spl. as in the 67-1 is a 4 inch group at the same distance and interval. I really never understood why until I got my 610. The long heavy barrle on the 610 made that cause for my poorer shooting with the 620 quite obvious. It's all about the swing weight of the gun. When your shooting rapidly, the higher swing weight causes you to drift the gun past the point of aim when returning to point from the recoil. Lighter barrels have less swing weight to fight and it makes these guns easier to shoot accurately in rapid fire drills. BTW, the best I have managed with my 610 at a 1/2 second interval at 40 feet is a rather miserable 7 inch grouping. If I slow down to a 1 second split, the 610 is a drill, however any time I try and increase my speed, all that weight in the barrel just slays my groupings.

Point is, long barrels are great for slow aimed fire and very easy to shoot accurately in this mode. However, they are not as good a choice for any setting where speed is a factor.