The latest-production SBHs made from about 2007 forward are more accurate than the older specimens. Easiest way to tell (on the large-frame Ruger SA series only!) is to look for the "lawyer's warning billboard" stuff on the barrel ("read the manual" and the like). If it's side-barrel it's older, under-barrel marks some engineering changes to how the cylinder is made - newer is better.
The same change originally happened to the mid-frame series (50th Anniversary 357 Flattop of 2006, New Vaquero) - side-barrel or under-barrel warning, all have the improvements.
The sole exception is the 50th Anniversary 44Magnum Blackhawk Flattop, the one not marked "Super". This interesting gun has "transition features" between the mid-frame and large-frame series. It has the new smaller grip frame from the New Vaquero, it has the improved cylinder, most had side-barrel warnings, it also has the loading gate "click improvement" from the mid-frame series. Nice guns but a lot of people don't like the smaller grip frame in a 44Mag. MANY got turned into home-brew Bisleys.
As to the transfer bar: the original non-transfer guns had a really sweet trigger and a simple, tough set of action parts. The New Model with a transfer bar was...well, not too bad. You can get a good trigger out of it and it too is pretty robust although you can break a transfer bar once in a great while.
Then Ruger came out with the transfer bar retrofit (for free) for pre-transfer-bar "Old Model" actions. And that was a total mess. Trigger feel was usually a disaster, reliability was way down.
It was that fiasco that gave the transfer bar Ruger SAs a bad reputation in many people's eyes! A real New Model with transfer-bar from the get-go usually has an acceptable trigger out of the box and it can be improved to a really wonderful point while retaining the fully drop-safe features.
Now. If I was buying one brand new Ruger SA today, it would be as follows:
Standard catalog Blackhawk large-frame, blue, convertible between 45ACP and 45LC. 5.5" barrel if I wanted to hunt with it, 4.68" if it was going to be a carry gun. Upgrade the sights, good grips, probably a Belt Mountain base pin, spring kit, done. I would keep the aluminum grip frame and ejector rod housing - less weight and less likely to pull the ejector housing screw loose under heavy recoil. That gun is still a large-frame and can eat 45LC+P monster loads that rival or exceed 44Mag power levels.
It can also take good 45ACP standard or +P personal defense loads, and spit them out at very strong velocities. Interesting things happen when you use short autopistol calibers in long revolver cylinders...the round goes through a "long throat" in the cylinder of almost an inch in which there's huge velocity boosts and no blow-by (tight smoothbore). Efficiency is just...yeah. Example, an S&W factory 2" barrel snub in 9mmPara set up this way will generate bullet velocities on par with a 4" barrel Glock 19...and Glocks "shoot fast" due to the poly rifling. Combine this effect in 45ACP with a 4.68" or longer barrel and you'll smoke the velocities seen in a 6" longslide 1911.
And unlike the situation in 357/9mm convertibles, 45ACP and 45LC require the same spec barrel, so there's no real accuracy compromise. You can also use semi-auto 45ACP mags as speedloaders, thumbing rounds into the loading gate
. It ain't "the cowboy way" of course but it's big fun.