It has been raised before in this thread, but to be more specific:
1.) Sharing an account:
I've got 4 PIDs in my (Mobipocket) account (for the other formats, usually it's similar).
Let's assume, I wouldn't even sell my readers, but just a "portion" of my account.
Meaning: I delete 1 of those 4 PIDs and hand that spot to another guy/girl.
So the account actually could be circulated between up to 4 parties at a time.
Each of those 4 parties would be able to access my library and read the eBooks on their respective readers.
Of course, distributor's argument will be, I'm the only one being allowed to have 4 units, but it's not allowed to spread over 4 legal persons.
My answer would be: Those 4 units could be owned by me, my parents and my wife. Why not 4 friends or colleagues? Or 4 total strangers?
So: Is it 4 units, exclusively bound to me or is it just 4 units?
2.) Lending my eBooks to 3rd party
Let's assume, I'd sell my reader(s) without any content.
But I'd grant the purchaser(s) access to my eBooks.
This probably would have to be for free (?), as I don't own the copyrights.
But still, it would be of significant benefit for those buyers, being able to access > 400 eBooks for free.
Of course, this might motivate them, to pay a higher price for my reader.
Again, I compare this to "dead tree" books. I can't lend them for a fee, but of course I can lend them for free to whomever I please.
The analogy to "dead tree" would be: I sell a bookshelf to you. It's expensive. But I'll lend you whatever book(s) you want from my library, so you can fill your bookshelf.
Of course, the analogy has one flaw: If I lend out "dead tree", I'd get them back at some time, whereas I couldn't control that with DRMed eBooks. (The purchaser always can keep a copy.) But then again: is this my fault? Did I invent this kind of DRM?