Looks like the Xbee shield V3.0 kit from NKC is not just a Xbee shield, you can use it as a Arduino Protoshield . With this kit there's lots of Components but only charge for 13.5 USD.
Xbee shield Remixed v1.1 is a original design of Seeedstudio. It got more feature than NKC'S and the size is smaller. You can still use the I/O pins on Arduino/seeeduino when Xbee shield is sitting on .
Anyway, i think both them can do the job but that little one can do more than the bigger guy.
A link to NKC Xbee shield v3.0 kit
http://www.nkcelectronics.com/freeduino-arduino-xbee-shield-v20-k21.html
XBee® Shield V1.1 by seeedstudio
http://www.seeedstudio.com/depot/xbee®-shield-v11-by-seeedstudio-p-419.html
Documents
http://www.seeedstudio.com/depot/images/product/XBee_shield_v1.1.pdf