And you can play back the clips in-camera off the card using the thumbnails; the FS-100 doesn't let you select clips via thumbnail so it's not so easy to know which one to play back.
And you can downconvert on the fly from the card to the tape, which the FS-100 doesn't let you do.
And you can play back your footage on an HD monitor from the card; can't do that with the FireStore.
And you can play back your footage in pN mode right away to see the slow-motion effect that you've shot immediately. Can't do that with the FireStore, you need to pull the footage into an NLE and process it before the slow-mo effect can be seen (although this will change in version 3.0).