Hello Corbin,
I do have a Merkel 141E in 8x57 JRS if that is the gun you are talking about.
I have nothing but praise for this gun, it is however a very light gun (3.1 kg) and I would not recommend it in 9.3x74R because the muzzle jump after the first shot makes it difficult to get a fast shot from the second barrel.

The gun is based on a cal 28 action which makes it very small and nimble, I do think that 7x57R would be an exellent choice for this gun.

My 8x57 has so far produced 4 shot groups of 2-3 inches at 100 m but I have only begun load development in this gun. Since it does have a adjustable barrels you should be able to get very good groups from this gun.
One of my friends have a similar gun in 9.3x74R and he get 1.5 MOA out of his gun, here in Europe other have reported similar performance of the Merkel 141E. But then most of the doubles here get scopes mounted on them which might make it easier to get good groups at 100 m.

Here the main use for doubles are driven hunts of boars, deer and moose and for this kind of game a 8x57 JRS is a very good option.

Regards,
Henrik