Even though I am a fan of cloud services, I think trying to keep all your data there is a fool's errand. For starters, your data is completely unavailable the moment you don't have power or Internet, for another it will be a very expensive proposition unless you really don't keep much data (and I suspect that's not the case as you have external drives in the first place).
There's definitely an advantage to having SOME of your data in the cloud; not only is it probably a more reliable backup than most users make, it's off-site, generally pretty secure and accessible from any internet-connected computer. But there are disadvantages beyond what I've already mentioned.
A more studied consideration of your work flow to determine the best candidates for file storage, combine with local storage, is still a wiser path on many fronts IMHO.