Also if your backing up data online consider restore time.
This is a good point, but you guys are missing the bigger point. This is Plan B or Plan C. I am not suggesting this as an complete alternative to a local backup. This is the fail safe if a real catastrophe happens. Waiting a day or two for a full restore would definitely beat loosing everything.
Buildings burn, equipment gets stolen and hard drives fail. If you are in the business long enough, you will come across these situations and more. Nothing suck more than telling someone that they have lost everything, or their only potential recovery option is a "clean room recovery service" for $2,500 per hard drive (e.g
http://www.drivesavers.com )
Regarding security, data is double encrypted before it is even transmitted. While it is possible, given enough time and resources, to decrypt your data and we are talking about a concerted NSA effort here, it is a safe bet that your data simply isn't worth the time for someone to try to steal.
For $50 a year, for unlimited storage, Carbonite is tough to beat. You can't even buy a decent external hard drive for this amount.
Granted, companies do fail. It would be worth a moment or two of your time every once in a while to test a restore of your files. I would say that local backup equipment fails far more often and has to be closely monitored.
Even if the on-line storage company goes belly up, I'm not worried. My data has little value to anyone but me. But for to me, it is priceless.
Also, if you have something truly sensitive, then you could exclude it from the on-line backup.