Yeah ,flossing transcends all types of fishing,fly rods are the deadliest of all.
As far as your reasons for not using a float ,none are valid ,floats are extremely effective in shallow water ,in fact up here we refer to the term short floating ,which is the technique where you run well up from bottom and present your bait above the fish .
As far as leader length ,anyone who uses a leader longer than 24 inches in any water conditions is playing THE GAME in my books.Im not saying all drift fisherman are flossing ,just when i hear people say that a long leader works better it makes me go hmmmm.
Like i stated before the only time i remove my float is when a pool is deeper than 20ft,i really dont see any benefit to drifting other than the occasion to floss fish and the need to perfect tying leaders.Its a simple case of physics ,fish sit on bottom, drag line across bottom and inevitably a fish with its mouth opening and closing will have a hook embedded in it.I know that drifting could be a productive way to catch fish but chose to use a float because it guarantees that im enticing the fish to bite .Im sorry you had to witness the vedder river long floaters but since we learned to floss sockeye a decade ago ethics around here have reached an all time low.
I wish i could stay and debate this with you but i have a sturgeon trip in the morning and have to prepare my secret baits.