I haven't heard of a .454 Casull version. I prefer the Governor: .45 LC, .45 ACP, and .410 to the Judge.
As for the LeMat, notice the idea is 2 totally different guns in one body. So your Judge won't stack up against the new Traveller LeMat with a center laser and snub revolver cylinder, or (my version) a gyrojet revolver with a shotgun/pistol cartridge center (and the opposite, also available).
Not to say that a 454 casull is the best but it is up there for taking out big game.
Now you can fire 45LC, .410 (brass) and 454 casull
The S&W Governor is a very good pistol. Big, stable, 6 rounds and can be a great revolver backup for your .45auto (uses moonclips for this caliber).
But the 454 with the right load and bullet can put some serious dents into armor (body not vehicluar armor, but it will mess up some armored windshields).
The problem with most 454's is that they are heavy (5lbs or more) and if you use the bigger loads or hot load your ammo, you better have some very strong hands (grip) and forearms (recoil) or use both hands. But if you hit the target it will be very obvious to everyone.
If you do your own reloading you can make about any caliber a shot (like shotgun) load. You can buy 9mm, 45LC, .45 auto, 44 mag, etc bird shot ammo. It has small BB's in a clear (or lightly colored blue, most common) cap where the bullet would normally sit.
In the beginning of the 454 casull rounds, the brass was too soft for the regular to high power loads and had fail rate (meaning the brass could not be reloaded or quickly ejected) of about 50% after shooting.
Today, it is appears that the fail rate only applies to the upper end high power or custom hot loads.
The S&W .500 is a good hunting, take down your target also. But there are not many speicalized rounds for it, unless you do your own reloading.
The Judge is a good all round revolver for most. Regular 45LC will kick enough that most will want a two handed grip, until they are use to it. Cowboy 45LC is easily handled by most, it uses BP for the poweder and is still powerfull enough to hunt with (taking out deer, coyotes, etc).
A 45LC P+ will kick very strong, and currently I would not want to shoot this round regularly though a Judge for 2 reasons. 1) It is hard on the hands, 2) it is hard on the firearm. (Note that the new Judges are supposedly able to hand this but Tauras makes no claims that it does, they have just strengthened the cylinder.)
.410 shot through a Judge actually kicks more than Cowboy 45LC and about the same as 45LC. A .410 slug will kick more than 45LC. There are home defense rounds for it also.
Short barrel and home defense versions are good for everyday carry and home defense. The longer barrel is better if you want to hunt with it.
The idea of why the Judge is a good home defense fire arm is:
1) It's a double action revolver, pull the trigger and it fires.
2) .410 rounds and 45LC (Cowboy) rounds normally do not penetrate or travel far after pentrating typical home walls (That is why a shotgun is normally the highest recommended home defense firearm.
3) You can combined different round in the cylinder with the typical set up being .410, 45LC, .410, 45LC, 45LC
4) It is less likely to jam than an automatic.
Of course there are many given reasons why one should not depend on a Judge for home defense, but I don't agree with most of those reasons. The only valid point is that it is a 5 round capacity firearm, but there are speed loaders (holds 5 shots for a quick reload).
A Judge is a good firearm (pistol) for those who want to shot/own something for many different things and do not know much about firearms.
If only they would make the Circut Judge (carbine style firearm) with a folding stock, it would be extremely popular instead of just popular.
A reason to consider a round like 454, 45LC, .410, (or even the .45auto in the Governor) is that they all can use the same powder and bullet. Just depends on how you want to reload and use it for.
Final point, there are 5 and 6 round 454 casull pistols out there. In the beginning they were only 5 but as technology advance and people were willing to carry a heavier and bigger firearm, they now make a 6 round one.
Dave Chase