I'd also think a closed fermentation will stay warmer, and form more esters during fermentation, if that's the goal.
My rum ferments are certainly slower, with fewer nutrients than a grain fermentation, so I'm even more concerned with sanitization. The only PH problems I've actually had are from all sugar washes during the dark days of hand sanitizer, and a PH buffer solved that.
Kinda off topic, but one note that I've discovered on closed fermentation, if you pick that route, is the need to open it up for a day or so before distilling, or agitate it vigorously to release the desolved CO2 in the wash. It's not so nice coming concentrated out of the parrot.