The best way to find out if flasher rigs increase your catch rate or not is to simply try them.I dont tend to use them much for surfcasting mainly because with more than 1 hook its easier to snag them up.Nothing worse than hooking a good fish on 1 hook only to have the free hook snag up on retrieval!
I can say though that thanks to a quality flasher rig I got myself into the 20lb snapper club while fishing from rocks in the sounds last new years day.
Flasher rigs are probably best for low light conditions such as deep sea or glow in the dark ones for night fishing.But being colourful also helps to attract the fish and they can be deadly for kahawai and kingys etc.Also the smaller rigs can secure fresh bait fish without even baiting them up.
It is important to buy quality brand flasher rigs because SOME of the cheaper ones just simply pull apart.
Anyways it doesnt hurt to try different rigs all the time and who knows you mite have a day when nothing but the flasher/ledger rigs get touched!
Let us know how you get on. FISH ON