omg...sorry i'm noob to this CM11S OS types between these 2 come across. can you elaborate in layman a bit more ? (e.g. "plain signed mode" is what?), also the one URL link you provided, has the same file naming too. Hence, i'm getting confused.
Follow the gizchina guide http://www.gizchina.com/2014/07/01/how-to-insall-cm11s-on-oneplus-one/
The part where it says to use the "cm-11.0-XNPH22R-bacon-signed.zip" file, follow my link and for the latest factory image, which is "cm-11.0-XNPH25R-bacon-signed.zip"
The links you've provided earlier are "-fastboot" which doesn't work with the gizchina method