IMO, it really comes down to what you'll use it for... I generally look at revolvers as "offensive" or "defensive"... just for "S&G's" a 2" barreled revolver is typically defensive, & a 6" or longer barrel is typically offensive... I hunt with an offensive weapon, & self defend with a defensive weapon... I have a couple 4" barrels one being one of my most used ( of non defensive weapons ), that is a stainless GP-100 that around home, it is my woods carry gun... there is not a lot that I would have to worry about defending myself against in the woods here in southern MN... the 4" barrel is very versitile, & the 357 magnum is plenty of cartridge
my woods gun for use in areas known to have animals ( 2 legged or 4 legged ) that I may need to defend myself against, forces a switch to either my Dan Wesson full sized Compensated 44 Mag snubbie, or my Ruger Alaskan snubbie in 454 Casull
can you hunt with a 4" or a snubbie??? sure, but with the shorter sight radius, it's just not as practical... can you defend against bear attack with a long barrel... sure, but if the bear is on top of you, before you get the situation neutralized, it may be more difficult to get the longer barreled gun pointing into a vital area in such close contact...
as long as I've gone this far... ( & you mentioned the Blackhawk )... IMO, a single action is great for an offensive, or hunting weapon, but not so good as a defensive weapon... if that bear is on top of you, & chewing on your arm, the pain & shock may leave you trying to pull the trigger to no avail, as the single action won't fire without cocking 1st.... I was watching something on TV about bear attacks in Alaska, & one woman was mauled while in her tent, & while she had a 44 mag revolver, she was unable to fire the gun, during the attack, & after alot of mauling, someone from another tent was able to shoot it with a slug gun ( the bear still ran off )... but the gun they showed, ( may not have been the actual gun ??? ) was a 6" barreled single action 44 mag Blackhawk...
point being... for myself, the 4" barrel is a good compromise length... not really the best at anything but easier to carry than a 6" or 8" revolver, yet still able to take aimed fire at shorter distances... not my 1st choice if self defence or hunting is a primary concern... then I either use a single or double action 6" or 8" barrel for hunting, or a double action magnum caliber snubbie for personal defense in the woods... I have a lot of revolvers, but don't own a 4" barrel in any magnum caliber larger than a 357 ( though I have a pair of 45 Colt Montados that are 3+ inches... but those are "fun" guns, not working guns... which brings us back to it's really what you plan to use the gun for ???