Regarding unlimited online backup Carbonite responded to my complaint about it taking about a month to finish a backup, writing in their e-mail that:
Carbonite backs up an unlimited amount of data, however users with more than 200GB of data selected for back up will find that completing their initial backup will take a longer period of time. Carbonite allocates more bandwidth to new users doing a typical initial backup of less than 35GB, and allocates less to users after their back up exceeds 200GB. ...
If I understand their response correctly, Carbonite also seems to double count files that have changed in calculating these limits (backed up files + changed files awaiting backup).
In any case, my approximately 175GB of data on my Macbook Pro took more than a month to complete the initial Carbonite backup, and some updates are running at least a month behind. (This is using my high speed FIOS internet connection with optical fiber to my home that allows me to upload a 1GB file from the laptop to a web server a thousand miles away via ftp in about 30 minutes.) So, for example, this same important file that changes daily shows the most recent Carbonite backup is the version of November 11, i.e., one month out of date.