Darne DR has been around since 1900, Geno. It's nothing new, except, maybe to you. When I was "Playing" in France, I got to shoot the model R Express, in both 8X57 JRS and 9.3X74 at the under-ground range at the Darne shop, and handle (but, not shoot, sadly) Paul Bruchet's 1910 built V action, in 450-500. My Proof house visit showed that the Darnes didn't fail the highest proof in Europe, at least not in the memory of the proof master working there at the time (1996).
It is easy to see the guys who will have trouble loading a Darne at a very early age-they are the same kids who get picked LAST for sports teams at school.
Good luck, Geno.
Best,
Ted