It seems to be possible now. With good reader (make sure it's the new one!!) I can transfer files to the iCloud section, evict them from the device so they are only on the cloud. Before I coulf not access on iCloud.com or pc, now both are there. So for doc storage it seems to be a good solution. Unsure if any other apps can do this? Apps like documents 5 can access drive and export to it but there is no way to evict a file which seems to be the key part.