Glad I could help.
Perhaps you could also ask your publisher to nudge Amazon about fixing their system to allow people who've previously downloaded a book to be able to download updates to it that are published to the same ASIN. I know a few other people, including one self-published author, have brought this up to Kindle Service/Support and haven't really gotten a straight answer as to their future plans for implementing this, so it can't hurt to have a publisher pushing for it too.
And if they get a definite answer back that they can share with us, that'd be great.
FYI, there are a few customer service reps that appear to be clueless about the situation (and seem to think it
should work even when it doesn't), while others are informed about what's really going on and have their facts straight. Therefore, feel free to let them know I tested it again right before I posted this (with the Windwalker book I have) and yes, it still always gives you the book version available at the time you originally purchased it only.
There really needs to be a better way for authors and publishers to get updated copies to their readers. I had thought this was one of the big pushes behind ebooks back when they were first starting out.
Thanks!
~Cherie