Thanks again everyone for the responses. Chris, once things calm down a little for me I may take you up on your offer, and send you my 853s and 943s, along with their various caps, for some testing.
For me, one huge advantage of the 4.7k mod, as opposed to 3-wire mod, is the interchangeability of gear. As I already owned a few SP battery boxes and 1/8"plug 831s, I wanted to keep my options and versatility open, hence my interest in the 4.7k mod.
It seems like there's consensus that some modification is needed for the 853s; and there's hot debate on whether it's necessary for (all) 943s, and whether it might actually somehow "degrade" the performance of the 943s. If I weren't already overloaded on mics I'd definitely try out some Church mics!