I think X1 is going on the right way for what is going to be the big next digital revolution, searching information.
This time, this tool is dedicated for searching in your emails, and to retrieve any file on your hard disk. For the last feature, it's incrediby fast, if you compare to the Windows search equivalent.
However X1 don't let you search inside the documents, maybe a next version. It's a bit pricey, but if you have a great quantity of information, this is a great idea.
I think it's the right way a bit like Google in your desktop, rather than WinFs, where you have to index yourself everything you want to retrieve fast. Yes WinFs is fast but where are you going to find the time to index thousands of thousands of files ?