Why do you need 4 different loops for this? It can be all done with just one (assuming that all the posts belong to that one category).
My suggestion would be to look into resizing on demand, I suggest this library: https://github.com/derdesign/mr-image-resizeI have also written a small WP plugin that hooks into default image resizing that WordPress does, that also generates images only when needed, and not on upload (add_image_size is still used, so no change in your theme code): http://wordpress.org/plugins/optimize-images-resizing/ (github).
Maybe you could make use of the code to get around this restriction (by explaining the reviewer what it does).
My only concern is that some users wil expect a big new feature or change, just because we rolled over to 4.x.x.
4.0 certainly brings some awesome new changes and I am looking forward to the release, there should be no major issues for the authors as only a few (3rd party) libraries were updated.
Envato should either provide their own, integrated support platform, or offer an authentication via Envato account (oauth).