I have been using iDrive.com for about 3 years with excellent results. The basic plan is now up to 2TB, and has no reasonable limit on the number of computers.
A backup system should be tested. I have performed several large (50~100GB) data restores with file compare on critical file sets to verify backup is working properly. (NOTE: I did have to set the option in TrueCrypt / VeraCrypt to change the file access date so iDrive could detect the file had been "touched.")
Things I like about iDrive:
1. You can create and use your own encryption key. While no system is perfect, this allows me another layer of protection on client data that may be on my systems. SET THIS FEATURE UP WHEN YOU SET UP YOUR ACCOUNT, otherwise you will need to have iDrive Customer Service reset your account, and all data will have to be up-loaded again.
2. iDrive will ship a USB HDD to seed / start the backups so you don't need to do everything over the internet. My up-stream speeds were less than 2Mb/s when I first signed up. The HDD option allowed for data to be backed up and on-line in just a few days rather than weeks of up-loading. This one time per year option may also be used to receive a restore HDD.
3. On-line restore operations normally downloaded at 10MBps or better, although there may be a significant delay before download starts. Single file restores are fairly quick.
