I have been fortunate to handle a good mix of double rifles in a range of big game calibres in both boxlock and sidelock. What immediately strikes when you shoulder a good double is that it seems to come to life and you feel you could tackle a fast flying partridge or teal, let alone some big and grumpy, even though it weighs 10lbs plus. If you look at most fine double rifles all the weight and thickness is at the breach end leaving the muzzle pretty thin walled.
Many of the german doubles have their weight much further forward. Allows for a steadier hold and a smother swing. Not surprising given that their main use will be steady shots from a highseat or a crossing shot at running pigs.
A british double rifle's job is to put two knock out blows into an inbound animal whose weight is measured in tons and you need to shoot a clay pigeon sized brain from a distance measured in feet.