Merkel SxS doubles are good things, and the company is to be applauded for keeping the genre alive at an affordable price-point.

However...

The claim to be a classic design unfortunately doesn't extend to the "proper" weight distribution needed for liveliness and reduced recoil perception.

Tapering the barrels from the breech-face (like a shotgun) rather than from a point forward of the chambers reduces weight concentration "between the hands" and forces weight towards the muzzles to achieve the necessary overall weight.
Sure, they can be "balanced" by weighting the buttstock, but that simply deadens the handling characteristics even more.

This opinion is worth only what you've paid for it btw.
My limited experience with Merkels is restricted to the .500 and .470 chamberings,
and I suspect the .400s and the .375s would be more comfortable to shoot.
A friend has a .450/.400 and loves it. I should pester him for a range session!