new guy:
Your assumption that double-rifle shooters discharge only one or two rounds in the presence of a PH is not well founded! My friends and I hunt boar and buff with doubles year-in, year-out, with nary a PH in sight!

I personally prefer ejectors, though only one of my doubles is so-equipped. The hand can be placed over the opening breech to prevent the spent cases ejecting if so desired.

Owning a quality double is a satisfying experience for a number of reasons, not the least of which is a deep appreciation of the gun-makers' art. To my mind, ejectors are yet another facet of the marvellous craftsmanship that is the double rifle.