Less chance of spooking fish when the line hits the water though IMO.
I don't get it.
You just described a float fishing set up (a float, 3 split shot to a leader and a single egg patter), and you're telling me that it is stealthier to have a bright lime green fly line hit the water behind it, and drift along with it... rather than having clear line suspended off the water where it never even touches the water? Interesting...
Honestly, the only time fly fishing is actually stealthier than any other kind of fishing, is if you are running a 12+ foot flourocarbon leader to a clear line with a small fly. Even at these times I still don't think it is stealthier than any other given method on spooked fish. I have done multiple tests on the island where I had vantage points on school of coho and brought along float fishing gear, spoons/spinner, and a fly rod. I can tell you, spoons and spinners despite what most people may think spooked the fish the least and created more hook ups (IF you casted PAST the school). Float fishing was second, and fly lines got the fish to scatter 90% or more of the time and after that I never hooked a fish. Tried it in a bunch of different orders, always the same result. If you're gonna float fish, do it with a pin or baitcaster. If you wanna glo bug, do a nymphing style so it still feels like fly fishing.
Koi fish, I would recommend either buying or tying new flies. Best flies for coho in rivers (this is even the order of importance I would go): 1)Mickey finn 2)Flash Fly 3)Rolled Muddler Minnow 4)California Neils (aka coho bugger) 5)Kelsey's Hope
Chum... almost anything will work. The thing that never fails me is a chartreuse marabou intruder.