Sync.com has security at rest and is fast becoming a global competitor to Dropbox (and is Canuckian, so everyone trust them... =] ).
I'd love to have beorg support syncing to it since I am intending to move off of Dropbox to it shortly.
I haven't come across sync.com before. I'll keep an eye on it!
Adding more sync services is something I'm frequently asked for, although sync is slightly painful to maintain - and a lot of support queries relate to sync, so I'm now very careful to promise/add support for more services.