Is a chin strap with a cup safer than an under-chin strap?

Many helmets have chin straps to hold them on.

One design uses a split chin-strap, where the strap splits into two forming a cup shape, one going just below the lower lip and one under the chin.

In my opinion, this is a more comfortable design as the chin strap is against the chin bone instead of pressing against the fleshy underside of the lower jaw.

I found a single link http://www.usyouthsports.org/images/CPSC_Hangman_s_4_point_chin_strap.pdf which claims that this design is safer for bike helmets as it may reduce some cases of strangulation in case a "yanking" force is applied to the helmet.

• Were there any other studies done on chin strap design like this for bike helmets?
• Is this design safer?
• Are there any bike helmets actually available with this chin strap ?