You're still not comparing apples with apples - Tegra 4 is several classes beyond what's present in those boxes.
Regarding what apps you feel should be included with the box, this is Android and everyone has their own favourite app to use for each task. We leave it entirely up to you to put on the box what you feel you need. It's also why we've been quite candid about recommending that you root M.O.J.O..
For a keymapper, for the time being we can recommend Tincore Keymapper.
Dolby Digital and DTS support: as you've found this is an app issue. All the apps need to do is allow pass through of DTS or Dolby and it will work - we know there's an issue with XBMC on Android as we've been talking to people there about it. It's possible we'll see a fix but there's no news yet on that front.
Tegra 4 is fast, but i have not found any 3D shooters out there that needs a 72 Core GPU, all those games play good on a PowerVR SGX544MP2.
But yes the interface is very fast, also booting up is fast, only we miss a off button, and write support for NTFS formatted External Hard Drives, because
now we have no use for a fast USB port (USB 3.0).