I am hoping the planned new "e" process will avert a problem I encountered earlier this year. I upgraded in the 4 day window for YVR/YEG/LHR. The cert was lifted at YVR. I had www check in for the entire trip but when showing the J boarding card at YEG for the LHR leg I was called on to provide a cert (whoa - it was taken at YVR !). I was told I was being denied boarding and, that's not all, since my original seat in Y had already been reallocated and indeed Y was full I was off the flight entirely - a major blow as I was travelling to a funeral. I left the gate to consider my position. Along came one of the gate agents presumably seeing the light and said OK "in the circumstances" I could board - what circumstences I had not done anything wrong to my knowledge. For at least 5 minutes this situation was very uncomfortable and there appeared no resolve or appeal. I later learned that the gate agent at YVR should have somhow marked my file but thats AC business not mine. I remain very cautious in the use of upgrade certificates ever since.