I've been lucky to pick up eight of them since 1979 or so. The first few from the shop I hung out at, the most recent off Ebay, where it was listed as "old baseball card" for $40 opener. Nobody else bid, probably because the listing had all the traits of fakery except grandpas attic.
As far as I know they're all tough. There are also two backs, and one may be harder than the other. I don't have both, but I've seen both in a small lot I got to look at, maybe 30-40 cards? Mostly vg, and I think the two backs were about equal. I should have bought at least one, but they were just too much at the time.
There's at least one uncut partial sheet out there. It was on the TTS cover in maybe 1980. Everyone local was a bit put out, the dealer found it on a buying trip to Boston.
The set was also in book of lists as part of a list of the 10 rarest baseball cards. And aside from the Wagner, Plank and Lajoie I think it's the only one that still has any major following.
Steve B