Mark you do not need ArcSDE 10.2.2, but what you do need is ArcGIS Server 10.2.2 which is the first version of ArcGIS Server to include the sync service capability for a feature service. I'm not sure on the minimum needed version for ArcSDE that you need to publish a sync enabled feature service, but I can confirm that I am using ArcSDE 10.2 (Not 10.2.2) and using the sync offline capability just fine.
I hope this helps.