So with a camera you have, you get half the resolution on film that you could get with a camera you don't have, with a film that's half the (linear) size???

I've compared a Bronica ETRS with 35mm back with a top-of-the range (1992) Nikon with a top-of-the range lens. The Zenzanon 75mm was a clear winner in sharpness and detail rendition - even over the same film size.
Leica lenses will perhaps be sharper, particularly in the wider focal lengths since they don't need the retrofocus compromises. But there are MF rangefinders too, not to mention LF cameras where no retrofocus is necessary and the film is even larger.

Try EFKE 25 in 5x7"...