Thanks for the detailed explanation.
And Yes, definitely stay away from MTP protocol then.
Would I be correct in assuming that if the eReader device is based on Android, then it is using MTP?
If so, skip all Android devices.
And that brings me only to Kobo devices as far as I know. That handles the Series column/tag/metadata.
I am mainly (only so far) reading books, so don't care about colour. Although it would be great to dispaly the coverpage in full colour
But if that affects the reading quality, then no.
And my wife is visiting China relatives for a couple of weeks, and since they do have way more products than here in Melbourne....