I have the Merit, and it is pretty cool, but have noticed with the screw ins that I tend to settle into about 2 sizes for different light conditions, and they are a lot cheaper. For a hunting gun dont even use a screw in, or use the 'shotgun aperture', so you have LOTS of light coming thru that hole. The 'ghost ring' effect of the sight without aperture is just fine in most cases.
In darker woods or overhead conditions too small an aperture will give you fits on even finding the target. IMHO, most people err on trying to use too small a hole thinking it will tighten the groups; not so!
You dont need to inlet a false tang to mount a tang type sight; scrape the mount area on the wrist to fit the underbase and woodscrew it on. I would like to try the Smith myself, I do like my 1898 Krag that is somewhat similar, though mounted farther forward. The open sight leaf of the Smith would be useless for me as it is too close to my eye.
You might consider the Williams 'target sight' from H&R), it has way more adjustment, and with target knobs is a snap to use. It is a very fine, and affordable upgrade.