Not quite as bad as I thought, though I would be more at Blackdown's level. 2 months is quite a lot of uploading.
you can throttle the bandwidth used by most backup software of this sort, so you can drip feed your data into the cloud if you don't want to piss off your ISP. and once it's done, it's done, except for whatever you add to your library later.
i know it's a trite thing to say but if you ever have to restore from a full backup, the time and/or money you've spent on it will be irrelevant. you know it makes sense! it seems like a day doesn't go by at the moment without some producer or DJ crying all over twitter because they lost a computer or trashed a hard drive and no longer want to live...