These are all very clever gadgets.
The only draw back I can see is that handy as they maybe, there adding to the " weight" issue most of us struggle with. A few ounces here or there adds up faster than you think. I have at least 6 tie down points on my Dry-Fly that I use a Trucker Hitch on. Bigger fly's or multiple fly's would requirie more gadgets adding more weight. Even if you like these type gadgets, I would highly recommend you learn the Trucker hitch if you don't alrady know it. Sooner or later you'll lose one or more of these items and you want to be able to go old school if you need too. ;)
I'm pretty handy/satisfied with the Trucker's hitch and for me, the extra weight isn't worth the conveience these little gadgets bring.
But each to their own and if you don't mind lugging it, then have at it ;D