I used to use Backblaze, but didn't like the connected drive limitation.
I'm using Crashplan on (4) Macs now. If you set "remove deleted files" to never, it will keep everything.
So far, Crashplan has performed well on individual computers with one internal drive. My Mac Pro with (8) external drives is not completing its backups to Crashplan. I'm not sure why yet, but will contact support.
In the meantime, I'm taking Arq connected to Amazon Glacier for a test spin. So far it's promising. I'll post again when I know more.
Music Producer – Re-recording Mixer
Rhumba Recorders/Murmur Music