TiAm - Have you tried to build with the CW Command line tools? The flip side is Cordova will have support for Crosswalk natively soon (hopefully next month) that should make it easier for developers to specify the version (since it's a plugin).
I'll try to build the space blaster with different versions of CW. If there is a big gain in CW12 (or I hear back from the CW 12), I'll push for the XDK to get CW12 support.