Nantonos:
Well, that would explain why some "third-party shields that don’t follow the R3 specs to the letter" might exist, then.
Heck, I would like to see just one example of a 3rd party shield manufacture that does follow the spec such that it can work with both 5v and 3.3v controller boards, just one in production shipping 3rd party example would surprise me to no end.
Lefty