Hi,
As I've said in a previous thread, I believe that feature parity should exist between core and compat, but not necessarely vice-versa (i.e. all non-deprecated features from compat should exist in core).
I've logged bug #55880 as a tracking bug for such issues. If you know of other useful features from compat which are not (yet) in core, please log bugs for them and set them as blocking for bug 55880.
Also, if you can fix any of the bugs on that list, feel free to send a patch. :)
Thanks, Strainu