It's not only the initial push or the initial pull from the cloud backup service that has to be considered. There's a bandwith requirement for each file changed on the system. Tarsnap does a very good job minimizing the cost of transfer, but it's obviously not marketed well enough to make lists with Microsoft and Google in the mix.
To illustrate the bandwidth situation, if I move files from a lower folder to a higher folder in a directory tree synchronized using csync it will treat the operation as a delete & copy reposting the files I have on my machine and using the bandwith twice. BitTorrent Sync will simply treat it as a move and adjust the metadata controlling the directory tree to logically place my information in the proper folder without having to repost the file.
With the closed source solutions listed above I wonder how they try and reduce the day to day bandwith costs. I know the scenario is based on a single restore request, but if that restore isn't built on the incremental updates then it's not much of a backup.
I don't disagree with the fact that it can and that the cloud a powerful way to get the job done, but that when implementing a solution it's important to understand how the technology works to accurately be able to calculate the cost.
The DoD went to the cloud for email etc. Well, during the summer of 2015 they upgraded Europe's version of MS Office to 2013. This upgrade was stored on servers in the states and necessitated redownloading each user's email history afresh. Since the DoD seems to mandate that internet connections terminate in the US, all of this traffic had to travel over the narrow leased portion of the transatlantic lines. This upgrade and congestion virtually shut down communications for Europe during crucial operations as the network was busy pushing the same office update to thousands of computers and then rebuilding their outlook databases from the original emails.
Yes the cloud can absolutely work and it does reduce the requirements of managing hardware, but it adds other dimensions that I think are worth pointing out and discussing. I'm personally a fan of cloud solutions provided they have localized repositories similar to a CDN. What are your thoughts on moving to the cloud?