I usually complain when things go wrong, but never when they go right until now.
I installed 9678 yesterday and a problem of not detecting web facets on a maven imported project has been resolved.
I have tried all other 8.1 EAP but they were unusable because of this problem.
The best thing is that IntelliJ now starts up in about 4 minutes instead of 15-20 minutes, I am assuming because of the improvements to the cache.
I am also very, very happy to see http://www.jetbrains.net/jira/browse/IDEADEV-33794 come along so I don't have to go in and manually clean up my 1.7 GB cache files.