OK, I guess I will be the first A$$ in this thread. Every time I see the thread I want so bad to type something but I have resisted. But now that it is on its way to 3 pages....
Let me A$$ure you-- the bag WAS not put on improperly.
I felt exactly as you prior to this happening, and my arrogance towards those who suffered a lost bag was the reason I chose not to take any preventative steps. There are videos on YouTube which show how easily the latch mechanism can be defeated by twisting and lifting the bag off it's mounts, so don't believe for a second that latch mechanism is infallible. The road I was on is fairly irregular surfaced, and it is altogether possible the speed I was travelling, coupled with the weight of the unloaded bag could have set up an oscillation-- I don't know. I didn't post of my misfortune looking for sympathy- I just wanted to share my experience in the hopes others did not suffer a similar loss.
It is interesting you would report how strong the bag attachment was when your Concours was involved in a crash. My prior bike, a Valkyrie- had Leatherlyke aftermarket bags which where also known to jettison due to attachment failures--- and oddly enough, when that bike was rearended and demolished by a speeding truck-- the Leatherlykes stayed on! Different situations do not always yield the same results...
Rawman, I appreciate your view on this, and I sincerely hope your "cautious approach to mounting the bags" works well enough for you that you NEVER experience a jettisoned sidecase. I disagree that it is "easy to put them on wrong" for any sighted individual showing a normal degree of care.
Bottom line: I love this bike. It's a great ride.