I had the opportunity to use a little bit my PH's double rifles.
In 2012, I shot my first giraffe with a Heym 88 in .470 Nitro express and Federal Trophy Bonded Bear Claw 500 gr. I really loved this rifle well balanced, not so heavy and so easy to shoot.
Later, I had the opportunity to use a Krieghoff in .375 H&H magnum. The rifle was nice to handle, but the regulation of its barrels was not good at all with 12 cm (almost 5") at 50 meters and the left barrel hit on the right of the right barrel ! The ammunitions used (PMP Soft Point 300 gr) where not the same used for the initial regulation so it might explains the result. However, I didn't try this gun with the initital load to see how the regulation was.
We shot several times 2 rounds to be sure about the result with these PMP and all shot landed in the same holes.
I killed with it a steenbok, a kudu cow and a black wildebeest cow.
Later, I handled it again and I had some problems. They didn't take care about their guns in this farm and the little mobile claw was so rusty, it became difficult to load cartridges into the chambers.
I would like a double rifle now. Hopefully a Heym in the near future.