We were having memory leak issue in our angular js app as well. And your blog did helped us.
One thing we observed in our application and i would like to share is; memory was proper if we were not clicking anywhere in app to view certain portion.
We were having anchor tags to view those portion, and clicking the same; it was changing our URL. With some more analysis we came to conclusion that , because of this URL change; IE was not able to GC the memory. Actually we thought this should not be the case, but it was happening.
So we removed anchor tags and used some other (tab btns)way to load the partial html views. That was not changing URL and it helped us significantly.
Along with this we started reloading the app, when it is idle for ~12 hrs. that helped us more.