Bisley Vaquero
The modern category of CAS is for single actions with adjustable sights. The Vaqueros - old, new, & Bisley - have traditional styled fixed sights and are most often used in the Traditional category of SASS competition. Depending on the ammunition used and the style of shooting they can be used other categories as well; any category a Colt SAA can be used in a Vaquero can be used in as well.
As far a the differences between the New Vaquero and the original, size is the primary one. The Vaquero was originally built on the same frame as the Blackhawk & Super Blackhawk, and like them was capable of handling magnum level loads in all calibers, including .45 Colt. The New Vaquero is built on the same size frame as the original .357 Blackhawk last year’s 50th Anniversary Blackhawk (not the current 50th anniversary .44 Magnum Blackhawk which is larger). The bad news, for some, is that the new model isn’t capable of handling the same heavy loads as the old model. The .357 is the largest magnum it’s available in and stuffing a .45 Colt with magnum level loads is a good way blow up your gun, and possibly your hand. Personally I don’t see that as a handicap – magnum loads are most useful in adjustable sighted guns anyway.
For its intended purpose the New Vaquero is a much better model than the old. The biggest problem with the original Vaquero is its weight and its somewhat uncomfortable grip. The new model is both smaller and lighter, handling very much like a Colt Single Action Army, and like the Colt it has a very comfortable grip. With the original Vaquero the only model that came from the factory with a comfortable grip was the Bisley Vaquero. The new Vaqueros are not available in Bisley form.