Q on bleeding/de-gassing xvalve

[mR.HaAPPY]

alright, so, i've been seeing a lot of threads about this subject, but none that really answer my questions.

ok, i shoot an xvalved mag with a drop and on/off... after games i just unscrew the on/off until the pin is no longer depressed and shoot out the leftover gas.... does this leave gas still in the valve, if so, is that damaging to the valve?
which of those bleeders dealies would you recommend? Pro disconnect, slide thing, pro connect? and what are the major differences in performance, maintance, and price?

[purplemag]

It is not good on the lines to leave the stagnant air(sounds stupid right) and pressure there. You will always leave about 400# (LVL 10 magic), and need to vent it out somehow. I have always just used a proconnect from AGD, and get the small burst of air, nothing to bad though!

[Bulldog]

AGD quick disconnect is usually the best solution.

[krafty]

Cooper-T makes a purge valve http://www.cooper-t.com/miscellaneous.html which works very well if you've got an extra 1/8" npt port on your on/off adapter.