Sorry guys...not exactly correct...racers really prefer the split back stay, where a single line comes from the top of the mast into an A shaped arrangment at the stern, around 10 feet above the transm.
Please note the double backstay where two stays come from the top of the mast is now an old less efficient system.
Most of the modern race boats use spilt backstays for many reasons. It became the choice of many, weight and stiffness the main reasons.
One of the reasons is weight saving as the system allows the use of purchases which are much lighter, instead of heavy jacks or the Titanic screw wheels.
Another reason is the fact that a split backstay transfers load onto the transom at 2 locations instead of just one, allowing less stiffening and thus weight reduction. It is also more versatile.
I don't know of any disadvantages of the system, only advantages. If you can, you're better off installing it. Also as someone said, in an open transom, or sugar scopper, with access thru the tra som, it's the way to go.
Me...I also think it's damn sexy.
Here a few examples of mine.
It is entirely made out of Dyneema, so i save the weight of the wire cable, has a purchase outside the transom and another one a 8:1 inside under the cockpit.
My backstay exits into the cockpit thru the floor, in the middle between the wheels. It's the blue line you see on the floor.
If you need more help just ask.