Hell, I wasn't going to jump in on this one...but will admit that I dearly love my levers & for forty years or so...I had the eyes to make them tick out to 150 yds or so with a good peep and suitable front sight bead, but at 77 yrs old, the eyes are history and I've resorted to scoping most of them.
What I miss most is the clean, uncluttered receiver and the way it fits snugly in a gloved hand; riding easily there at 'trail arms' through the deer season. But for sighting with some precision, open sights with the issue notched rear went bye bye by the time I was 45.
I mounted Lyman or Williams peeps then: tangs if I could get them, receiver types when I couldn't and got another 10-15 years of that lovely uncluttered receiver. Now it's scopes for the big bores.
Here are a few from the stable now: 1st pic: from the top, all Marlins. The .30-30 336 Texan scoped with Weaver's 2.5x, next down is my 1894 in .41 Magnum Leupold 2.5x Alaskan scoped, 3rd down is my 336 in .44 Magnum, with another Leupold Alaskan, and last is my 1894 .357 with a Williams WGRS top mounted in the scope mounting holes. That .357, as sighted is still a good grouper out to 75 yds or so. The 2nd pic is of my Century LImited Marlin .22 with a Williams receiver Fool Proof mounted. The 3rd pic is a Winchester Model 65 in .25-20, with one of Lyman's tang peeps on it. Lastly, here's a .38-40 Marlin 1889, peeped of course and a fine shooter if you don't push it too hard.
I love & prefer 'em clean or even "peeped", but the old eyes hold the clincher card eventually, & I had to go to the glass. Best Regards, Rod