I've been carrying and using SAA type revolvers for more than 40 years. My choiceof barrel length is based on experience over those years.
Th longer 7 1/2" barrel guns do shoot easier due to the heavier weight and "hang" of the longer barrel. This normally results in better accuracy. What you give up is ease of handling and carry. That long barrel just is just long enough to make hip carry a bit more diffecult. this is particularly true if riding in a truck as the long barrel tends to dig into the seat and hang up on things when entering or exiting. On horseback (or ATV) this is not as much of a problem, but still more difficult than the shorter barrels. When walking it is slower to clear from a hoster and can dig into your side, leg or the ground when kneeling or sitting.
The longer barrel DOES add a few feet-per-second of velosity, but this is seldom an issue at normal hangun ranges.
The 4 3/4" barrel is just the opposite of the 7 1/2" as it is a joy to carry on your hip, is easier to clear on a draw, weighs less and comes on target a bit faster. However, that shorter barrel is less steady when shooting and requires a lot more consintration to hit well with. At normal handgun ranges this is seldom a real problem, but the longer barrel does have a slight accuracy advantage (for most shooiters) when shooting paper or animals.
To me, the 5 1/2" barrel is a compromise that doesn't perform as well as the longer OR shorter barrels....overall. It is lighter and handier than the 7 1/2", but doesn't carry and handle as well as the 4 3/4". Accuracy is better (slightly) than the short barrel, but not nearly as good as the longer. I will say that (for me at least) the 5 1/2" guns look and balance better than either the short or long barrel SAA's. The 7 1/2" is just a bit too slow to get into action while the 4 3/4" guns are just a bit too "whippy"......the 5 1/2" beats both and (once again....to me) is "prettier".
For my use I normally carry a 7 1/2" gun when handgun hunting to gain the better accuracy and dn't have a need for speed.....I put up with the carry problems to gain those advantages. Hunting is normally a more deliberate game that typical woods walking.
For daily use I carry a 4 3/4" or 5 1/2" gun (the shorter gun when riding in a truck, the 5 1/2" when mostly on foot) as I feel the better handling and slight increase in speed from the holster is more important when shooting is more "unexpected".
They all have their uses and I own and shoot all three.
