On a Double with something like a 9.3x74R/500 NE combo it would seem to be tuff to get the handling of different barrels related to rifle weight to work out.I would guess a 9.3 barreled rifle alternate Double would handle like swinging angle iron!!!

Dunno how the balance and handling of a heavy Double with alternate Shotty barrels would do either but I would like to handle one to see!!

The switch barrel rifle concept would seem to work better in this regard. A 300H&H/375H&H would intuitively seem delightful to handle for a PG/limited DG hunt(no ELE)