Are the downloaded files full resolution, or are guests stuck with web-sized versions?

Full resolution — that's one of the features Snaptide lists on every single plan, free included. When downloads are enabled, guests get the real files, not compressed previews. This matters enormously in the photography world, where the entire point of delivery is handing over print-quality images. It also means your storage usage is honest — you're storing the actual files, and that's what fills your allowance, so plan capacity around full-res delivery.