These comments are generalities, for which there are many exceptions - some of whom are fellow correspondents on this forum. But I believe, from my experience, they are generally true observations.
Most double rifles are double trigger designs - certainly the vast majority of English models and copies are. Unlike Europe, relatively few Americans today have a lot of experience using double triggers. Their instinctive employment, particularly in a high stress situation, takes a lot of practice. If one does not have a double shotgun so equipped, that means a lot of rapid second shot drills with the new double rifle. My experience has been that good intentions are all too soon overcome by recoil and expense. Also, over the last few decades, relatively few Americans spend a lot of time over open sights. Most, however, are superb shots with a chosen caliber and telescopic sights. Compared to what I saw while stationed and hunting in Europe, the American rifleman will also spend much, much more time at the range than will the typical European hunter/shooter. He tends to be absolutely compulsive about accuracy. As a result, transition to a similarly equipped .375 is usually very easy, and he employs it very effectively on dangerous game in Africa. What he likely has almost no experience in is driven game using drillings, double rifles, combination guns and the like - something many Continental hunters are familiar with on driven hunts where boar form part of the bag.
Most doubles can be equipped with at least a red dot type sight, but many shooters don't want to do so because it is not "traditional." (I have been disparaged for scoping my Blaser S2 - a double designed for scope use - by "traditionalists" who argue it is the "improper" use of a double - whatever that means.) Assuming the novice dangerous game hunter intends to use his new double traditionally, that brings us back to square one and the need to be totally comfortable using open sights to take game under field - not range - conditions. Again, such proficiency can absolutely be developed - we did it regularly in the military with young urbanites - but it takes effort, a lot of ammunition, and some mechanism to create field conditions. And most new doubles do not come equipped with a drill sergeant.
I remain convinced, for a first time dangerous game hunt, a hunter should do everything in his power to insure the first shot is exactly where it needs to be. Every successful and proficient deer hunter in this country can do that effectively with a quality scoped .375. That precision is usually not nearly so easily achievable with a relatively unfamiliar rifle action and sights.
