Chad, I agree that the jake should not be hard on the engine, but I'm not sure I agree with your explanation of how it works. From the Jacobs Vehicle Systems website... When activated, the Jacobs Engine Brake opens the exhaust valves near the top of the compression stroke, releasing the highly compressed air through the exhaust system.
Little energy is returned to the piston, and as the cycle repeats, the energy of the truck’s forward motion is dissipated, and the truck to slow down.

http://www.jakebrake.com/technology/engine.php

 They also produce something they refer to as a bleeder brake, which sounds like what you are describing.  http://www.jakebrake.com/technology/bleeder.php

When coasting, the engine keeps pumping air through it.  Pumping that air requires energy which slows the vehicle.  When the air is compressed on a compression stroke, most of the energy is returned to the cylinder as the air expands on the down stroke.  The bleeder system you are describing works by never allowing the pressure to build, and thus not providing any rebound.  Energy is removed by requiring the pumping of the air.  With the original jake brake the valves were closed during the compression stroke (requiring energy), but then at the top of the stroke the air is released suddenly (thus the noise).  The air then does not help to push the cylinder back down.  Both systems help to slow the vehicle, but I think the true jake will provide more braking power than the bleeder setup.