My order of preference in the more affordable doubles:

Searcy (for strength and accuracy)
Heym (for slim design)
Merkel/Chapuis
Krieghoff

It is true that the Merkel is made from a 20 gauge shotgun action which has been re-hardened. Rigby use the same action for their double rifles. There was an article all about it in Safari magazine about 2 years ago. The stories about Merkels coming off face seem centered around Merkels which were chambered in 416 rigby. Merkel has discontinued that chambering.

Chapuis may be guaranteed to never come off face, but I saw one that was off face after less than 200 rounds. Yet I shot another couple of Chapuis that shot extremely well at 100 yards, which is a bit more than one can expect from most doubles.