Dusty Miller,
If the airline loses your ammo,regardless whether it's standard or improved,you've got a problem.375H&H [standard]will chamber/fire in the improved version,albeit with some velocity loss.Unless you can buy the -exact- factory brand/weight/lot of ammo that you originally sighted in with,you'll have to re-sight the firearm.
What I have done with some firearms after sighting with handloads,is to take several different factory brands/loads and test them in the firearm,I then
record this info on a file card taped onto the buttstock.
I have wondered about ballistic advantages with the improved version for North American hunting.
It sounds like potential longer case life is THE primary advantage.