Flat mono line?

[FrequentTyer]

I was re-watching Joe Humphrey's nymphing video and started wondering about his suggestion of using a flat mono line. I have heard him talk about this in interviews and he spends a page or two discussing it in "Trout Tactics." If I understand what he is doing, he is using a long length of heavy flat monofilament as an extension of the fly line. The argument seems to be that it will sink fast and create less drag since the diameter is about half of the diameter of the fly line. In "Trout Tactics" he writes that you can actually cast the mono if you have weighted nymphs and/or splitshot on the leader.
Has anyone used this rigging method successfully? What monofilament do you use, and how do you rig it?

 

[Lonewolve]

Doug swisher used to advocate using flat mono in building a leader, im not sure you can get it, i also thought cortland used to make or distribute it years ago

 

[sandfly]

used to use it for shooting line way back when. still have some somewhere in my room..