I too have grown to appreciate imperforate stamps more as I've aged.
Might be partially a function of pushing the completeness urge into more areas. So over the last year I've been pursuing flat-plate imperforate coills (US that is). These are notoriously not in the main sequence of the Scott catalog, but lurk about the middle of the Specialized with the private perfs (which do not really interest me).
I also started to pursue fully and partially imperforate errors in US Airmails as a way to keep doing something with that collection which was, after all, pretty easy to complete since it is a very small universe, even when one collects all the booklet slogans and such. So they're a way to keep the hunt alive.
Since every thread deserves a picture or two, here is an imperf flat plate coil, Sc. 368V. somewhat long section with a pasteup lower down.
I think I'd better go dust my scanner now.
