I got the Mojo Sights, but just didn't really like the Tandem Aperture as much as I thought I might. The front sight just blocks out too much of the target because the metal surrounding the aperature is so thick. For example, if you were shooting at a 12inch pie plate at 100 yards, you can only see a few inches in the middle of the plate, but you lose your frame of reference since you can't see the edges of the plate. I'd way rather just have a normal but fine edged front site (much finer than a normal chunky mosin front post).
Since I haven't really found an iron sights solution I've enjoyed, I've mounted a scout scope with Darrell's Scope Mount. It's been rock solid so far, which is more than I can say for all the other mounts i tried. I'll probably leave it that way forever since my rifle just shoots to high for the iron sights at 100 yards (even with the mojo).
One thing that I'm curious about it the Huber Concepts ball trigger. My M38's definitely gotta pretty mushy pull. The ball trigger is supposed to be adjustable and nice. I don't know if I'm going to put more money in my mosin though... it was my first gun and I did a lot of experimenting with it. Now its time to save up for a Remington 700 or something.