Before going to a web-based solution, you might want to make sure that you really, truly, have web access *all* the time. That's less of a concern if you are switching between stable offices, but it's a huge concern if you are planning to work at random places like coffee shops. Murphy's Law says that the more critical web access is, the more likely it is that your favorite location will have a line out the door, or will have its own access go down, or something.
There's also the personal preference issue, of course. I went to a paper system in part because I realized that while I could use electronic tools anywhere, I really didn't want to. Somehow I found electronic tools overly intrusive.
YMMV.
Katherine