I believe that the double is rather a rifle for close distance combat so the sights should be designed accordingly. If You want to use it at longer ranges You have to make compromises. A big front sight is quicker to align but of course will be useless at longer ranges, just like a scope sight with high magnification will never satisfy at very close distances.
The fiber optic sights are also a compromise, the gather light so will be useful in low-light conditions but they are neither as sturdy nor as accurate as a finer brass bead.
So the sights should be choosen with the kind of Your hunting in mind.
Just MHO.

Kalunga