Late response,
I like your setup as described, but not seeing how you plan to handle delivery of images to mobile?
imho, getting mobile right is critical. My mobile traffic by regular members jumped 24% in a space of two months after cutting images for mobile (using imgix) and implementing a lazyload solution (lazysizes.js) for graceful loading.
Also, from my point of view, having had to deal first hand with the rise of screen resolutions since 1995 - not keeping the original full-size image dimensions as uploaded is a trap. The day will come where 1600x1600 is not good enough. It will come.