I wouldn't worry about it. Skifta.com have changed their authentication server, which has broken the current version of the add-on anyway. And all references to it from the main ReadyNAS website have since dissappeared, so i'm thinking Skifta has gone the same way as Orb as far as Netgear are concerned.
I wish Netgear would choose a provider AND BLOODY WELL STICK TO IT, or just avoid partnerships like this altogether. Fed up of creating accounts for these types of service only for Netgear to pull support for them without warning or notification. It's getting old.
NAS1: Netgear ReadyNAS - Pro 4 [FW: 4.2.26 - Drives: 4x SpinPoint F4 2TB - RAM: 4GB]
NAS2: Netgear Repertoire U4 (Chirpa Special) [FW: 4.2.26 - Drives: 4x WD Red 2TB - RAM: 4GB]
Router: Netgear WNDR4300 [FW: v184.108.40.206] | Switch: Netgear GS108Tv2 [FW: v220.127.116.11]
UPS: APC BackUPS ES-700uk [1st Gen]