Thanks. I was curious.
I do most of my tagging in the OS X version, when I do my periodic cleanups every day or so. On the iPad and/or iPhone I only tag the obvious things when I first create a note, the ones I can remember and type in rather than select.
I also sprang for the premium account, which means I don't suffer from syncing lag when I open up the iPad version. I have it set to keep all my notes stored locally.
Good luck on your search.
P.S. Have you ever tried using the Everclip app for collecting information? If you are doing a lot of research in one session, it's very handy.