We did exactly the same thing. Switched over to O365 assuming that One Drive would work for us, only to find out there's no client, it's been being promised forever, was promised at end of 2014, and still nothing. And, only to find out that even if the client comes out, the 1TB we have per user is limited to 20,000 files on the entire drive. It's 2015, not 1998, is this really a limitation that can't simply be lifted?
Anyway, in the absence of a client for Mac, we're looking at how much more money we will have to spend now to go set ourselves up with another company that has a product that will work, like Dropbox.
Is there not any way to get some kind of realistic update from Microsoft? If you promise a product by a certain date and don't deliver, isn't some announcement in order for those of us trying to use your products?