This is the first time I have used breezer-style dropouts, personally they are not my taste however the frame is not for me. I know builders fillet-braze them, is brass the better option than silver here? You can build up the brass/bronze however the silver seems to be a bit stronger. Suggestions?
Brass will be stronger (unless we're talking about an Ag like Parr's Fillet Pro which is just as good) but these types of drops are really best suited for tig joining. Brass can, and does, work but it's not optimal for hooded drops.
The only real concern is that there isn't a really good mechanical connection for the cs/drop join and it's at one of the highest stress points on the frame and like I said, those drops are designed for tig welding.
Still, it will probably be fine with a good braze and a good size fillet.