Calling All Large Cent Experts

Also, the top of the T in CENT is dropped and tilted slightly in S-279, while perfectly level in S-278.

Adam--you added that just as I posted!

An early die state S-277 without cracks and weakly struck areas is a very scarce coin indeed, far scarcer than the MDS and later states with their many cracks and areas where the design is completely missing, resulting in the so-called "12 star" obverse with S1 gone due to die subsidence. The corollary is that the terminal die state (Breen's State IX) which has huge reverse rim Cuds at UNITED is also extremely scarce to rare.

Knowing this (that an EDS S-277 is something you're probably not going to come across in the wild!) you can usually go off the date diagnostics alone for eyeball attribution. On paper the 278 is only slightly scarcer than the 279 (at R3 vs. R1) but this doesn't directly translate to the bourse or auction floor and some dealers will put a premium on the S278 just because of that little R number.

As an aside, 279's are actually rather scarce in their LATE die states, so if you see a 279 with die cracks, Cuds, or obvious signs of a late die strike, that's a good cherrypick to make!