hum, don't know, i use't to use only flor corks, but now use only nomacorc,
they can be kept either laying or standing for long periods of time, 1 & 3/4 better then 1 & 1/2
Dawg
Like @hounddawg I switched to Nomacorc a few years back, so my experience is with that product.
I haven't read any literature on the subject, but if there is no cork in the "cork", I don't expect that humidity matters. I can store the bottles standing up, although horizontal storage is engrained in my bones ....