I personally don't care for the spirit levels in the front sight, they are to much distraction, and either seem to reflect to much light (external) or take up to much of the front sight (internal). I do like the Shaver front sights for their size of the globe, and he does offer a fair amount of usable recticles.
Good point. The inside diameter of the globe, especially relative to how much "stuff" is inside, makes a difference in how the shooter can "see", but very much dependent on the individual's own eyesight, and also somewhat subjective.
What I have found is that for an internal level to be "seeable", I need a globe that is larger than the common Lyman 17A size, like the Browning, Heilmann, and smaller Shaver, to name three that I am aware of. With the somewhat larger globes like the DT, Baldwin, and larger Shaver, I can see the internal level OK. The Browning is a 17A size, but works well with its external level. I had a Heilmann, and it is a nice neat little globe sight with an internal level, very much at home on a smaller rifle, but it went down the road because I just couldn't see well with it. The Lyman 17A is still made, and an excellent value at less than $40. If anything, the newer ones are even better made than earlier production.
I find Shaver's inserts too fine for my eyes, meaning the thickness of the surrounding metal. There are other makes of inserts that work with his sights, especially the common 17A size.
The traditional Sharps front globe with the pivoting detent leaf spring was a royal PITA to me, always catching and bending. For me function trumps pure tradition.
Here is a pic of a Sharps and Heilmann sight, neither of which I currently own.
Lots of choices out there.
Paul