Interesting discussion. Coming late to the party, I'd toss in a few tidbits:
American doubles, in general, were built more like tools designed for hard use than were most British doubles. But Americans and Brits also adopted different approaches to maintaining their guns. Americans shot their guns until something broke. Then back to the factory, or to the local gunsmith. Brits, after the season was over, would send their pair of whatevers back to the maker for whatever attention they needed. Even if they were in perfect working order. Preventive maintenance . . . sort of like visiting your dentist a couple times a year vs waiting until you have a toothache. Drives American collectors nuts, because American collectors want "original". Well, if a Brit double needed reblacking, it got reblacked . . . so no longer original. Just a different approach. Speaking here of the real classics, not the hardware store guns on this side of the Atlantic, nor the "keeper's gun" on the other side.
Re American originals: Ted, surely you're not forgetting that the Remington 32 is essentially a copy of a French OU: the Petrik. Not nearly as popular as your Darnes. But then that particular design is still alive and well today in the Krieghoff OU's. And for a gun that came along late, in terms of American classics--it was really the last of them--the 32 didn't sell very well. But then OU's weren't all that popular when the 32 came out either.
The problem with a lot of American classics, especially the entry level ones--Sterlingworths, Trojans, Ithaca and Elsie Field Grades--is that they may have been attended to by the village idiot rather than a real gunsmith who knows what he's doing.
IMO, the best buys in the used gun market--in terms of guns that will sustain a lot of use (take a licking and keep on ticking)--fall into what I'd call the "older but not vintage" category. Ithaca SKB, Browning BSS, Miroku-made Charles Daly, and the Italian "B" guns (Beretta and Bernardelli). Hard to go wrong unless you get your hands on one that's really beat up. There's nothing on the market today--again, IMO--that matches what you get in an Ithaca SKB Model 100 for the money you'll pay. You do need to live with a single trigger (but a very reliable one) and extractors. But those guns now have half a century of use behind them, and they've stood the test of time. And when it comes to modern ammo, they'll eat pretty much anything you feed them.
