I find that this works very well at CO and NW. I have flown both frequently of late, and I am almost never at the gate when F/J is called to board. I arrive sometime in the middle of coach boarding, and it is nice to jump the queue.

I have not encountered any problems with others using the elite line w/o being qualified, nor have I encountered any resentment. The signage is quite clear, so I don't see how people could think you are cutting or otherwise acting inappropriately.

Side note: Agree with the Duck re: allowing priority disembarking for int'l J pax. It is surprising that DL hasn't adopted this policy.