I have a different perspective. I've been using my own stack and mnemonica for about 10 years now, so you'd think I don't need the watch. But guess what? There are some other things that you can do with the watch. For example, a trick I do, but takes a hell of a bit of mental gymnastics, is an ACAAN that utilizes a move that looks pretty much identical to a rollover pass. I haven't received my watch yet (it's on the way) but looking at the pictures I've already figured out how I can quickly "glance at the time" and know what card I need to split at for the pass.