SpiderOak seems like a nice company, and I somehow find their stance on "unlimited storage" reassuring - they don't
offer it. And they don't just "encrypt everything", they use zero-knowledge encryption, and even avoid cross-customer block de-duplication (which could save them significant storage costs) simply because it would be a potential security problem.
I've got their blog
added in Website Watcher, there's occasionally some really interesting stuff there.
Unfortunately the client software isn't perfect - it's a bit on the slow side, even if it's been improved a fair amount. I know the guys want to keep their code as portable as possible, but it'd be really really nice if they added NTFS USN Journal
support (can speed up scanning for changes after system boot by craploads) and would split into a service+GUI so the backup can run without being logged on...
Oh, and offer smaller plans. The free offering is a bit little for me, but OTOH I really don't need 100GB of storage. I can understand why they don't want to go into, say, per-gigabyte prices... But perhaps 10 or 25GB increments?