Fantastic work Joe.....I literally played around YESTERDAY with the PSA Pop report for A&G sets and haven't finished with SGC but there are some oddities in the PSA Pop report.....which is probably an understatement.
Your dates and theirs agree on........
N5,N6,N7,N8,N11,N13,N21,N22,N24,N26,N27,N28
You differ on......
N2 (you 1889, them 1888)
N4 (you 1889, them 1888)
N9 (you 1888, them 1887)
N10 (you 1888, them 1890)
N25 (you 1890, them 1888)
N29 (you 1889, them 1888)
N34 (you 1890, them 1889)
The other sets they have dated.....
1886....N16,N17
1887....N1,N3,N35
1888....N15,N18,N19,N20,N31,N33,N36
1889....N14,N34,N38,N39,N42,N43
1890....N23,N30,N37,N40,N44
1891....N12
Not sure what the source of their data is. I know there are ATC pages on dates of issuance for some of the 20th century tobacco sets but not sure if they exist for the 19th century. I have a dozen or so JPG's of those pages for some nonsports and T206 sets.
The PSA census of graded N1-N44 cards is outlined in the picture below.......
Almost exactly 10-1 small to large A&G cards graded by PSA. Not sure what SGC or the combined look will yield but I'd assume something similar. The oversized format cards are super tough which Mark and you already identified. If you assume that submissions are rational, then the small sized cards are 10x more plentiful. As a collector of all the A&G sets, my totals are about 10x small to large as well (1140/133).
Interestingly, looking at the pop reports, on the small-sized A&G's, 5's and 6's are approximately half of the cards graded. For the larger-sized A&G's that census drops a notch to 4's and 5's. Anyone who's graded some can probably attest to the difficulty of the oversized cards.