I just picked up my two-tone Grenson Stowes. They are built upon an elongated, chisel-toed last (which doesn't come across in the pictures) and fit very snuggly. In those two respects, they remind me of shoes on the C&J 337 last. There is quite a bit of wriggle room for my toes, but I think going down half a size would result in a fit that is too narrow.
In sum, I think they're keepers. Thanks Chris!