This orientation causes me to dump the contents of the front zipper pouch once in every five or six times I grab the bag from the right handle.

OK, I looked at my empeg bag. The front zip runs vertically if the bag is picked up using the side handle (i.e. it's not wraparound like the main compartment zip). If the zip is open, stuff will fall out whichever way round the zip closes. If the zip is closed, nothing will fall out whichever way round the zip closes. I'm not sure what would be changed by changing the orientation of the zip...

Peter