[t206hound]

I'm collecting the SC460-42 subset (just missing two) so I have a bit of knowledge on this.

First off, the no overprint subset only has 47 subjects, while the overprint subset has 109. So, there are obviously fewer subjects, but that doesn't account for print runs.

There are also twelve subjects (exclusive twelve) that appear to have a substantially higher print run than the remaining 35 no overprint cards.

So, in general population, my observation is that the SC460-42OP are much more prevalent than the non-overprint counterparts, and that if you are looking for those that are not in the exclusive twelve, even more so.