OwnCloud vs. (Drupal + SabreDav)

I have not had any luck in adapting OwnCloud because of the lack of community knowledge and documentation. So I took some time to strip it down to its components. In the end OwnCloud just seems to be Web GUI for SabreDav. After a little hunting and research I found that I could get a more robust and customizable solution by using Drupal as frontend (authorization, uploads, CalDav UI) for my own SabreDav server.

Both Drupal and SabreDav have enough documentation, community and interest by php developers to get me over any obstacles I believe. SabreDav has an excellent OOP plugin system and I found some sandbox code for Drupal SabreDav and CalDav modules.

The only real difference I can find would be that OwnCloud uses Mirall and another protocol to sync things.

Anyone know of any really big differences or missing features that would arise from doing this? Am I wrong in thinking that OwnCloud is a wrapper for SabreDAv?