It would be good if custom editors would work for child classes, wouldn't it?
Unfortunately that's something you should tell Unity, as that has nothing to do with NGUI.
As for UITable and Grid's sorting function being exposed... to be honest if you want advanced sorting then you should consider just doing your own positioning logic. UIGrid especially is meant for very trivial child arrangements.
It's not a bad thought though, I'll probably add something like that when I'll re-do the grid and table logic in the near future. They're both scheduled to be upgraded to something more robust and flexible.
