I own Ruger single actions with both the plow handle and the Bisley grip frame. The biggest difference is in how they handle recoil of the big boomers. The Bisley grip frame allows for a higher grip to reduce the amount of leverage that the uses against you in recoil. The more vertical angle also keeps it from slipping and rotating in your hand like the plow handle does. This can be either good or bad.
I tend to prefer the Super Blackhawks Dragoon or hunter grip frame for anything up to a stiff, but not heavy, .44 mag load. The longer grip fits my hand well and the slipping actually reduces the felt recoil. When the recoil increases, I find the Bisley much more comfortable. My .475 Linebaugh with a plow handle grip frame will literally rotate so forcefully with heavy loads that the hammer will dig into the meaty part of your hand between the thumb and first finger and draw blood, unless your grip is very firm.
In a New Vaquero, I don't think you will see any real benefit in the Bisley grip frame unless you simply like the way it fits your hand. Some like it, and some don't. Give one a try. if you don't like it, I guarantee you can find someone that will swap you a standard grip frame for you Bisley. Good luck!