Bleeding brakes....

What is everyones opinions on the speedbleeders?? I currently have two brake jobs at hand, both at the same point. On the duster, I have bled and bled,... also used a mighty vac,.... and still very little brakes. The entire system is new with the exception of the lines/hoses. My second project is my neighbors 47 Willys truck. Same scenario. Bled and bled. Pedal will go to floor first time. you can pump it up, and feel pressure.. but let it sit a few, and its to the floor again. All new parts on it too. I bench bled both MC's... I had my wife and child help me with the duster by depressing the pedal,... but still cannot get adequate brakes. I did not know if anyone here has used the speedbleeders to eliminate the risk of error due to the helping hand,,... or foot rather. In my opinion, the mighty vac is junk,.... or my ability to use it sucks!. When bleeding, do you slowly depress the pedal? or jam it down hard? I must still have air trapped in both systems.

Triggerjay