Ian,
There's several of us in the Model 39A Club (find that thread for some fine reading) who have the Skinner peep sight. In general, the sight is well thought of, delivering pretty good performance. There's a few reasons for the good reviews.
Peep sights will give you a longer distance between the front and rear sights. That's a good thing for accuracy. The peep sight geometry supports the Mark I Eyeball (M1E) better than tang sights. That's why you see loads of military rifles with peep sights and none with tang sights past the early days of WWI. The construction of the Skinner is all you'd want too.
In short, go to the Skinner for the peep sight.
Report back, please, on how things work out,