Many Winchester Grand Europeans have had serious problems with poor regulation. I would consider one only if it could be demonstrated to be reasonably well regulated.
Agree with the above. Given poor regulation and the fact that most came silver brazed at the muzzle (which makes re-regulating a PITA at best), I'd wade carefully. I've heard of it being done on a few rifles, but that's a project and certainly something to be aware of. If it's proven to shoot well with a reasonable load, then this is less to worry about.
Most double rifles for rimless cartridges use a small, spring-loaded pawl (or sometimes just a rounded wire) that recesses back into the extractor housing as you push the cartridge in. If you're careful (or lucky, depending on who you talk to) it snaps back into place in the notch. In the few I've seen, it doesn't seem like the sturdiest setup.
I danced with a 375 H&H vs 9.3x74R double decision, and ended up with the 9.3 mostly because I wasn't convinced by the extractor pawl on the 375. Plenty for what I needed it to do at the time - but of course that's not what you're asking. DRs sure are fun.
There are some neat doubles out there in 303 British and 30-30. I think the key to keep in mind is the regulating load. Even though there are doubles in some more common calibers, you may not have access to loads with the right powder, pressure, and bullet. Pressure is definitely a consideration in longevity of a double, and compared to the big safari loads, the 30-06 is up there. Anyway, you may get some more input from folks with more knowledge than me in the DR-specific category of this site.
