Hi PAmtmman,
Don't get mislead by the notion of a "waterproof" pan. It may seem that rain would be the killer and diverting it somehow the solution but the hydroscopic nature of black powder is such that it is the humidity with rain or snow that dampens the powder. No pan design protects against that humidity. I too like the separate pan idea of the Davis lock but with respect to performance, Jim Kibler's late flintlock will be the best you will encounter among modern made locks. As I described in my link, you can turn the Davis lock into one that is very close to a fine original English lock but it takes work and know-how. I have a original English fowler made in the 1820s by Fields. It is a very good quality gun but nothing like the Mantons, Purdeys, Richards, Nocks, etc of its day. That modest and generic quality lock puts every modern-made commercial flintlock to shame except for those by Kibler and Laubach.
dave