I've been using the Prime storage thing for three or maybe four years now. Since you can include RAW files, it recognises Canon CRW as well as CR2 files, along with DNG and PSD files as images within the unlimited allowance I used it as online backup for all my images. It was OK for the first six or seven years of my digital files, when I was using the 6 MP 300D and even my 8 MP 20D. Those 12 bit RAW files weren't too bad, as they worked out at about 1 MB per Megapixel. Also back then the number of images per year were not super high. It only took about three months to upload the about 70 GB of images from 2005 to 2011. That's about when I gave up on it, as it went up from 15 /year, to eventually 170 GB year. I also moved home and my upload speed went from slow to glacial.
So I just gave up, I still have what was uploaded on the Amazon servers, but I'm not adding any more. Even if I just went to uploading new files, I would be creating them about five times faster than I could upload. So I'm now just back to multiple copies of the files across several external HDDs.
I already have Flickr, where I upload anything I might want to share as 1280 px long edge Q80 JPEGs exported from LR.