I see there is support for ActionBar in the Google Supplied SupportLibrary (SL_AB) - added with API 11. http://developer.android.com/reference/android/app/ActionBar.html
I am wondering if I should use this instead of ActionBarSherlock (ABS).
Is the functionality in SL_AB comparable to ABS?
I would love to remove the external library dependency (ABS) from my project, and it seems to me this is a good approach (but not one followed by many people, and I am wondering why).
The original Support Library simply isn't that good for ActionBar usage, giving ActionBarSherlock a right to exist. Google will soon (Or is it here already?) come with a new version of this ActionBar support, as announced recently on the Google I/O 2013.
I think you're still looking at the original, not so good, library and thus you should use ActionBarSherlock.
Transferring your question to the near future, asking if you should use the new ActionBarCompat Library, or ActionBarSherlock: I would say It's more a matter of personal preference.
(Of course...) Google advises people to use this new library instead of ActionBarSherlock. However, they do bring this with the message that there is nothing wrong with ActionBarSherlock and that you shouldn't go through the trouble of replacing it in existing projects.
If you want to invest learning this new support library, it is the advised way to go. However, personally i think its a waste of time. Lots of people are already familiar with ActionBarSherlock, at lot of help, tutorials and questions about using it are on the internet to get you going and using the new lib. Probably won't even give you any real advantages.
Probably, by the time the new library is as easy to find help for, as ActionBarSherlock, people hardly need it anymore since more and more developers will drop supporting older versions that don't have an ActionBar by themselves.