I shoot Vaqueros in SASS ... .45 Colt, in recent years.
There's a distinct difference between what is known as the "
XR3" grip, and those commonly found on most single-action Rugers of the
last 40yr+.
It may be a matter of personal preference, but most aficionados (
and while I'm typically excluded from this group, in this case, apparently not) prefer the "
XR3" grip.
I recently acquired a brand new .41 "
Flattop" (
"Flattops" and "New" Vaqueros typically come with the "XR3" grip) in 4.625in bbl. I've shot a "
deer pistol" league fer a few years now ... usually two guns ... usually one of 'em, .44 Mag ... loaded to basically Winchester U.S.A. 240gr levels ... shot from a Bisley Hunter ... and a 4in 629. In working up some "
warm" .41 loads, at typical factory levels, the 4.625in handles as well, if not significantly better, than my Bisley Hunter did (
albeit, with less powerful ammo ... but the weight difference, IMO, more than makes up fer it). It's also remarkably accurate.

Almost fergot to mention, I've also shot this .41 with the "
warm" loads one-handed, with no ill effects.
A good friend once suggested to me that the recoil of an SAA is managed to a great extent by way of what we often negatively view as "
muzzle flip" ... the grip (
particularly the non-Bisley, and when gripped properly, with the pinky underneath the butt) does absolutely nothing to counter this. However, such guns, shooting "
warm" loads, also exhibit remarkably little recoil.
IMO, a longer bbl tends to counter this "
feature" ... to some extent. However, at the same time, a longer bbl adds mass, as well ... so I don't believe it's a 1:1 kinda thing. In my experience, the shorter 4.625in bbl merely "
flips" more (
not nearly 'nuff to put a dent in yer noggin', though! 
) ... whereas, the longer bbl tends to drive rearward into the palm of yer hand. At which, I realize less fatigue, with the shorter bbl.
IOW, my best guess is, you likely won't see much difference on the target, or on yer hand (
the edge, to the shorter bbl) with various bbl lengths. At which, choose the one you believe you would enjoy, most.

I can't speak to DonT's point. All my .45 Colt loads have been under 500fps. I have won a few "
poker" matches ... even using "
match" loads!

... but past that, I can't guarantee what he says is not prevalent ... in .45 Colt. In .41 Mag, I would highly doubt it.

I also recently acquired some dual-cylinder .45 Colt/ACP "
New" Vaqueros ... again, .45 Colt loads are unremarkable ... however, with the .45 ACP cylinders, even "
match" loads exhibit remarkable accuracy ... possibly one of my most accurate pistols, I own. At which, if such things are a concern fer you, 'er even not, IMO, a dual-cylinder .45 "
Flattop" would be be WELL worth the extra $100.
P.S. if ya have some factory .45 Colt "
cast" loads ya'd like to try in a 4.625 "
XR3" Ruger ... such things can be arranged.
