I'm on C9 and have been for some time now. Lots of nice little tweaks from C8. I'm doing examples in C8 now and there are a few hints I miss. The ones that spring to mind are
A) ability to set fonts in IDE specifically to make them bigger. Sounds trivial, but really isn't.
B) open-file doesn't need you to navigate to the correct directory. Just type the file name. The RED system finds it for you. So let's say you want to examine some code in netweb.clw, in C8 you need to know where it is, C9 you just type netwe.clw into the open file dialog.
C) new search option allows you to search the files in the same directory as the open file. Or search based on the RED. Very useful.
There are a lot more, but you can really only articulate them when you go back and they're not there're anymore.
In short, think of C7 as a typical version 1.0, which makes C8 version 2. Good but not perfect. C9 is version 3 which adds a lot of polish ( and 3.1 is coming any day now.
Cheers
Bruce