Just curious - why wouldn't just creating a compressed copy of the full regular Project folder work? That's what I do all the time with my friend, and we have NEVER had a single issue doing this.
We both have X2a and use the default Per-Project Audio option that stores all audio clips for a project in a sub-folder within the project folder.
All we do is create a new compressed folder, copy the project folder (with its audio sub-folder) to the compressed folder, then transmit to each other. Our particular method uses FTP from one of my web sites, but any such FTP process would work the same, or if the other party is local, just either burn to disc or toss onto an external USB drive.
Once copied to the other computer, the receiving party would just go into the compress folder and copy the transmitted project to the Cakewalk Projects folder. Once there, the project can simply be opened in Sonar.
Since this is all standard Windows stuff, it just works, which I find more comfortable than trusting the creation and use of the Cakewalk 'Bundle' process.
Bob Bone