Can I install takju ROM on unit with yakjuxw?
The answer is yes, you can install a takju ROM on a yakjuxw device.  For that matter, you can also install a yakju ROM, or one of many other custom Galaxy Nexus ROMs (e.g. Cyanogenmod) on a device that originally had yakjuxw.

I have personally flashed both yakju and takju ROMs on my Galaxy Nexus, which originally had a yakjux (Canada) ROM.  The only possible issue is that flashing a new ROM may erase user data from the SD card (pictures, SMS messages, wifi information, etc.).  So you may want to back up your data before flashing.