IDEs really are much better at this than grep or ack. My experience has always need something that can perform symbol resolution, and something more powerful than grep or ack wins here. You may be ack-guru and and do that on the fly, but the rest of us mortals are not willing to put in the effort when some other dev has given us a command line tool, an editor plugin, or an IDE to do that for us. Its all about how much time you want to spend feeling cool and how much time you want to spend getting things done.