I'm in favour of keeping things as simple and uncluttered as possible.
That being said, I think that tracking magic-item use is important.
Towards that end, Grandpa's Cards again play a handy role.
If you physically possess a card for each magic item, and then "tap" the card when you use it, that provides a handy reference for book-keeping purposes.
Now, granted, you have to mentally track how many magic-items you are allowed to tap, but since this is directly proportional to your number of action points (plus one after 10th level, plus another after 20th), you should simply be able to look over at your pile of Action Points (spent plus unspent) and know how many "taps" you're entitled to.
One fewer thing on the sheet to clutter things up, but still a simple way to keep track of things.
Plus, the cards have all of the rules right there, to keep things nice and handy. No need to crack a book.