I think the longer barrel lengths take better advantages of this cartridge than the snubbies that it has mostly been chambered for IMHO.
That's actually fact more than opinion. The BBTI guys did really quality testing on the factory .327 Federal ammo and when you cut the barrel off under 3 inches, performance drops like a lead zeppelin.
However, I do have to disagree with you about it "mostly" being chambered in snubbies: Ruger's SP-101 is over 3 inches by a hair, and wrings a heap of power from the round. Only Charter Arms and Taurus ever marketed a .327 snubbie and both are well out of production. The Taurus guns in particular are hitting the market at outrageously low prices from retailers such as CDNN out of Texas. As much as I love the round... I am not a snubbie guy, and have zero interest in them.
As for Ruger, keep in mind that the .30 Carbine Blackhawk was first rolled out for production in like what...1969?! It's been "out of production" more times than anyone can count, but they continue to make it available when they do runs of them. I have hope...I have extreme
hope that Ruger continues to back this excellent cartridge with it's three different .327 Federal revolvers.
As for it being like the .30 Carbine Blackhawk -- it is, really, a LOT. But the few differences make it a better choice for some... and a worse choice for others.
.30 Carb B'Hawk only comes in black/blued. I call it black because Ruger's "blue" these days isn't like a classic, deep blue. My revolver was born in '08 and it's...black. The .30 Carb only comes in 7.5" barrel, too. Extra length gives you longer sighting plane and a bit more velocity -- but makes the whole package a bit unwieldy depending on what kind of use you intend for it. For sure, the .327 B'Hawk is a prettier revolver and easier to handle with 2 less inches of barrel. The .327 also gives you 8 shots over the .30 Carb's 6 shot cylinder.
If you are buying factory ammo, the advantage: tough call! .30 Carb ammo used to be a real cheap, easy affair. Mountains of surplus stuff. In fact, that's the reason that Ruger introduced a .30 Carb B'Hawk to the market -- even before they ever built & sold their first .45 Colt. Hard to believe, but true. These days however, .30 Carbine ammo is just as expensive as anything else. Except, perhaps... .327 Federal.
Also, full-spec factory .30 Carbine has a reputation for sticking in the cylinders of .30 Carb B'Hawk revolvers. This is due to the high pressure -- but more so, the tapered .30 Carb cartridge case. Wiping out the cylinders on a .30 Carb B'Hawk -OFTEN- helps a lot. And yeah...major PITA.
In that respect, .327 Federal B'Hawk blows away the .30 Carbine. And at the load bench, the .327 Federal kills the .30 Carbine. More bullet selection, better bullets, much
easier to handload. However the brass is difficult to get a hold of...or expensive if you simply buy Federal factory or Starline brass. .30 Carb brass is much more plentiful.
I won't buy a .327 B'Hawk because I own a .30 Carb B'Hawk. But you couldn't talk me out of my .327 Federal GP-100 no matter what you did. And I'd take my .327 GP-100 over TWO .30 Carb B'Hawks any day of the week.