Marrakai, regarding peeps and doubles, John Taylor promotes them on pages 220-221 of AFRICAN RIFLES AND CARTRIDGES, both for doubles and for magazine rifles.

Wide notch rear sights are about the only ones I've used for years on my iron-sighted rifles and they are my favorite type of rear sight. For me, next in line would be peeps.

As for your $100 wonder, ugly is as ugly does, and from what I remember, that peep sighted double gun of yours Does! Neat gun. Now Peter really has some options...