I've got one of these echobit flips on my truck. Mine gave me nearly 8" of lift due to a very crappy (pretty much straight vertical) shackle angle.
If a guy had a proper shackle angle (gotta move the rear hanger forwards), then you'd get about 6" out of it. I'm gonna pull mine off and put in a set of 64" springs with enough added arch to give me 6" with a normal shackle direction. I want a smooth ride, but I want lots of stability for towing, which this echobit wouldn't offer me.