Sorry to post a third time, but I was looking for @Quuador’s post in a thread that I often reference for Japanese unlimited vs 1st edition.
From the thread below, it seems like XY9 and XY11 might also be harder to find in unlimited. Not sure how they compare to XY8 and XY10 though.
Aside from the massive thread on unlimited E1 on E4, pichufan has also put together a blog post about unlimited E1 here. As far as I know, it mostly summarizes all the information that was gathered in the E4 thread. I don’t think any new information has surfaced regarding the release of the cards.
These are the best sources I am aware of. (All of them originating from E4, of course)