I find my self missing the ability from other hosts to combine multiple objects for printing in one go. Relying on external tools to arrange and combine objects into batches seems a bit rigid and will end up clutter your file collections with duplicate date in multiple files which seems a bit redundant. The hassle of download, combining, editing, and uploading can also be avoided. A batch could in fact be it’s own thing with a number of object and their transforms (position, rotation, scale) which could make versioning individual objects in a collection easier for power users.
Anyway love Astroprint sofar and look forward to see it grow add cool features.