At this location, we use OwnCloud application on the in-house NethServer. We find it integrates easily and sync with the calendar function in Thunderbird/Lightning. Our main function though is to have a file store where we and our customers can upload/download files, using desktops, tablets, etc. For this requirement it works very well.
Pydio was not suitable for some users, and OwnCloud we thought was better than Seafile for sync. We did look at using others,(cloud versions) like DropBox, Google+, etc, but wanted something that we can control, and could be placed on our own hardware.
NethServer includes a one-click install of OwnCloud, (see here: NethServer: ownCloud 1-Click install – NethServer ) and with the NethServer community, if things went wrong, there is excellent help available.
We have been using OwnCloud on Nethserver now for about 3 months and it is very stable, upload/download of files from desktops is quick - a 244MB .mp4 file took 7 seconds to upload, and 11 seconds to download, tested using two Mint 17.3 desktops, one for upload, 2nd for download.
We have not had any problems like this; our field engineers use the Hotel’s own connection, however we do use VPNs back to the NethServer, before using OwnCloud.