Also, is there any reason why any of these sorts of things can't have Linux installed, and, for the things that need it, use an external keyboard, wired or wireless? For a while I was looking at this OTG cabled keyboard for Android devices. I decided against it (and hope that the Pyra keyboard will indeed be decent). I don't even remember the name/manufacturer, and it was pretty cheap. Anyway, to use something like that with either the Shield Portable or the XD (why is that not a smiley?) is a tradeoff, losing portability for the ability to use the keyboard, or using a lesser option when away from the keyboard, and using the keyboard when it makes sense (but why not just use a full size computer at those times?).
I dunno, I use my Pandora at times when it would also make sense to use a laptop or desktop, but the Pandora is more convenient (size and weight are great, I can walk into another room and type while someone is talking about something, then shove it in a pocket and do whatever, etc). Most of those times are not related to gaming and rely heavily on the keyboard, so, if anything, Pyra/Pandora sales to people wanting to do that wouldn't interfere with the sales of the other options, but these others can interfere with Pyra/Pandora sales when it comes to gaming.
Edit: What I was really getting at is they both have their audience, and there may be some overlap with Pandora users. I only need one, and it must have a keyboard AND gaming buttons.