Opportunity is missed by most people because it is dressed in overalls and looks like work. - Thomas Edison
A lot of the correct way to address this would have to do with the amount of data we are talking about. But in general here are my thoughts.The main concern for me on "online" back ups is 2 fold:Connection or the speed which you can upload/download "ALL" of your data in the event of a drastic issue on site (fire/complete drive failures/flood/etc). This is a issue 2 ways, what is your upload speed and how long will it take you to upload all of your data and how long will it take daily for it to keep up. That said will it affect your other needs for your internet connection. The other side is keep in mind some of these online service throttle the speed, so you could be waiting awhile to put 1tb in the cloud or retrieve it. If you create gigs a day like we do often it could be tough to keep up with it being able to be uploaded in a reasonable amount of time. Just something to consider. The other issue is how much do I trust someone else with my data. I wouldn't discount this for a second. Seriously assume someone is looking at all your data. True or not, I wouldn't hand someone my data without being ok with them looking at it. Cause it very well could happen.Now to address your original concern, yes that is a decent way to say redundant without heavy cost of server/etc.
With the RAID drives, I went with enterprise grade. With a fail rate at around 1.4 million hours. I was thinking of going raid 10 when I get the next drive, that is slick, FYI.
i checked the power usage of the server and the cooling fans for it. Servers are energy hogs.