I would like a .450/400 DR myself and as often only one gun can be taken in luggage, it would need to double as a somewhat plains game rifle as well. Maybe the longer shots would be difficult.

But even though this annoys some purists, if the "regulation" of the two barrels is "insufficient" at longer ranges, there is not reason why the rifle can be used at longer ranges as a single shot. As long as you know how one barrel shoots at different ranges and it is in line with the scope or sights. Obviously two barrels is better than one, but if only one barrel will do it, no different to a single shot hunter, except at closer ranges you have two barrels.

Just my ideas on the subject.