That reminds me of CrashPlan. They throttle uploads and deny it – and they have been promising a native Mac client for years. Scanning of new / changed data is rather slow too. I was testing SpiderOak two or three years ago. The client was awful but slightly less awful than CrashPlan's Java-based client.

These days, I use a mix of Backblaze and Arq (with Amazon Cloud Drive).

Backblaze is great but versioning is limited to 30 days. More versioning is probably not feasible, i.e., other cloud backup providers with unlimited versioning have to find other ways to keep their data usage under control.