According to Reuters, "Research has found that of 56 cats examined over a six week period, the cats’ ability to catch animals was markedly reduced with the bibs. The bibs prevented 81 percent of the cats from catching birds, 45 percent from capturing mammals and 33 percent from taking amphibians and reptiles. Some 89 percent of cats in the study became quickly accustomed to the bib." You can read more research here.
I'm not sure how easy it will be to get cats to wear this--I mean, how many of us have had to put the lamp shade on our pets after a visit to the vet? That generally goes over like a fart in church with cats. Personally, I think the birds are still at risk for being so overcome with laughter when seeing a cat with a bib that the local Cooper's hawk will swoop in for the kill.