Posted By:
Tim NewcombBob and I were (are?) planning a collaborative article on the set, to update and correct Lew's pioneering work. I have collected a good bit of info from Bob, from Scott Brockelman and other experts on the set.
Then I got involved co-writing the M101-5/4 issue that's coming out in the next issue of Old Cardboard. One card-related article at a time is about as much as I can handle (I have a job, although I do get summers off 
).
But I still want to get back into it-- this summer if possible, with Bob or, if he is too busy, maybe someone else.
So let's treat this as an exploratory step toward a survey of some kind. In another thread (maybe next week) I'll send out a request for people to report on their M116 holdings, and formulate some of the key questions I think we need to investigate, and ask for questions that have occurred to others to ask. That way, instead of doing it piecemeal, we can do it a little more systematically.
In the meantime--
Matt, your summary was quite good, but let me make a couple of clarifications [my comments in brackets]:
____________________________________
Series 1: Blue and pastel backgrounds - blue more difficult [YES]
Series 2: Blue and pastel backgrounds - pastel more difficult [YES]
Series 3: printed with blue or black ink (on backs) [my belief is that the blue backs are more difficult, contrary to some assumptions]
Series 4-18: no variations [NOT QUITE: SEE NOTE BELOW]
Series 19-24: more difficult [FOUND WITH "300 Subjects" Backs only, which you are calling Type 3]
____________________________________
NOTE
[SERIES 1-18 are most commonly seen with one of two backs. But cards with Type 3 "300 Subjects backs" have been seen in some of these series, most notably Series 1, and also a few others]
The questions you ask are important:
Were all 288 cards re-issued with type 3 backs? [I AGREE WITH BOB HERE-- IT SEEMS VERY UNLIKELY THAT ALL 18 EARLY SERIES WERE ISSUED WITH THE "300 SUBJECTS" BACK OR WE WOULD HAVE SEEN MORE OF THEM. I HAVE BEEN WATCHING FOR BACK ANOMALIES FOR SEVERAL YEARS NOW, AND THE ONES I'VE SEEN FALL INTO VERY DEFINITE PATTERNS. THEY SHOW UP IN SERIES 1 MOST OFTEN BY FAR, NEVER IN SERIES 2 OR 3, IN A FEW OTHERS ABOVE 3 AND BELOW 18. BUT NOT ACROSS THE BOARD]
were the McConnell and McQuillan variations only available with the Type 3 back [I WOULD LIKE TO KNOW THIS TOO-- WILL ASK IN THE SURVEY-- RIGHT NOW I SEE NO EVIDENCE THAT THEY EXIST WITH BACKS OTHER THAN THE TYPE 3]
If so, are they really any more scarce then any other Type 3 back?
[THEY MAY NOT BE ANY MORE SCARCE THAN THE TYPE 3 BACKS IN THE LOWER SERIES. SINCE ALL SERIES 19-24 CARDS HAVE THIS BACK, THOSE CARDS ARE MORE PLENTIFUL THAN THE MCCONNELL, MCQUILLAN (AND BATES AND SEYMOUR) VARIATIONS. AND THE TYPE 3 BACKS IN SERIES 1 ARE SEEN MORE OFTEN. BUT CARDS IN SERIES 4-18 THAT HAVE TYPE 3 BACKS MAY WELL HAVE COME FROM THE SAME PRINTING AS THE RARE VARIATIONS, AND MAY BE JUST AS RARE.]
More to come soon, as soon as the M101 article is put to bed!
Tim