Expecting all the drag to go away is not realistic. The pads are going to remain in contact with the rotor. If opening one bleeder frees up both brakes, you're holding pressure in the front brake lines, probably all the way back to the master cylinder. Try loosening a line at the master cylinder and see if you get a pressure squirt there the nexct time the brakes drag.

I would be reluctant to use ANY sort of aftermarket pressure control device that the factory engineers didn't include in the original system- - - -chances are it was invented by some hotrodder who is going to solve all your problems by selling you something! P.T. Barnum would have been a good parts salesman!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!