I mapped shield to one of the face buttons and grab to R, and now I'm actually using the shield. It's still incredibly uncomfortable though. I'm using a regular 3DS with the Hori silicone protector that makes it a little easier to grip (and travel with).
This already seems like a million times better than the plan going into PAX East this year. I was there, I can tell you it wasn't pretty. I just hope the PAX schedule gets posted before the sign-up time so I can work out if something else is happening at the same time.
It was just posted, and the Cards Against Humanity panel will be happening at the same time.