I really hope that you'll take this in the way that it's intended and not as someone wishing to rain on your parade. However, since you say that you're new to double rifles and can afford a good one ($16k), I'll be blunt.

1. Want a good double (and most would rather have something with good resale).

2. Likes the idea of using said double for hunting elk at timber ranges in the US (good idea) as well as Cape buffalo in Africa.

3. No problem with .375 recoil levels but may be sensitive to .470 levels (while few will admit it, this is true for most).

4. Has $16k to spend on it.

Given the above criteria, the solution to your quest is one of the easiest there is, but you're looking in the wrong direction.

First, a double rifle is a double rifle, not a bolt rifle. A high pressure belted rimless round like the .375 H & H is intended for bolt rifles, and does not belong in doubles. Holland & Holland introduced a .375 Magnum for double rifles at the same time they introduced the Belted Rimless for magazine rifles - it's the .375 H & H Flanged Magnum, and is still produced and chambered in new rifles. If you stick with your two original choices (I would not), get the .470, and grin and bear it.

Also, while I like engraving and pretty wood too, you need to understand that build quality is infinitely more important in double rifles, and that engraving, pretty wood, and other bells and whistles don't equal build quality. My .400 is engraved and has wonderful wood, but sometimes price dictates compromise. I would willingly sacrifice engraving and wood grade for price if I had to, but never build quality. You can get much better quality (and much better resale) for the money that you have to spend.

Get a Heym PH Model in .450/.400. Hornady offers factory .450/.400 ammunition now, if that's important to you, and they also offer components. Woodleigh bullets are also available in the correct weight and diameter. The caliber is legendary for it's effectiveness on all African heavy game, and is ideal for your stated needs. Recoil is slightly greater than the .375, but substantially less than the .470, or .416 Rigby. The .400 is easier than the .470 to become accustomed to and to learn to shoot quickly and well and, because it's easy to feed (.450/.400 ammo and components are available from just as many manufacturers as .470 is now), It's one of the most sensible double rifle rounds that you can choose today. You'll use it more effectively because you'll enjoy shooting it more.

The Heym PH is offered in .450/.400, can be had for the money you have to spend, and fits your requirements much better in a substantially better quality rifle. Yes, it's a plain model, but you can have it built to your dimensions and choose your own wood and barrel length, fore-end type, etc. Build quality is the best that you can get for that price.

No, I don't own a Heym. I'm an English gun guy and have never harbored a desire for one of the new guns in this price range, although I've handled and shot most of them. If I had to buy a new double in this price range though, I'd buy the Heym without a second thought. I would not consider the Blaser under any circumstances. The Heym, Merkel, Krieghoff, and Chapuis are all better guns, and the Merkel can be had for half the money you're talking about. Judging from your location, I've a hunch I know who the dealer is you've likely working with. My opinion of the quality of the Blaser is the polar opposite of his, and he's definitely not a double rifle guy. Just remember that he is a salesman.

By the way, if you need to have a recoil reducer in the stock on a double rifle, you either bought too much gun or it was built too light. I hate what those things do to the feel and handling of a double rifle and would never consider one. The .450/.400 doesn't need one.