I find this all very interesting and enlightening, as I'm eventually going to package & self publish chapters from Worm.
I think I'd be skeptical of the offer from the outset, because the amount offered to be divided among the KDP Selecters is (as far as I've observed, please feel free to correct me) wholly at Amazon's whim... so it's like, possible outcomes are:
1. I take the deal, make my book(s) available, it takes off, Amazon offers decent amounts, I get a decent share.
2. As above, but my books don't take off. I've no more options, have shot myself in the foot.
3. As #1, but Amazon doesn't offer a decent amount. I've no more options, have shot myself in the foot.
4. #2 & 3 combined.
I'm a bit of a pessimist, being inclined to buy into #2 or #3, so it just doesn't appeal at all.
Afraid I don't have much more to add. Thank you for sharing, Ubersoft.