I try to install the updating using Command Centre, and eventually I get an error dialog that states:
 
C:\Program Files\Cakewalk\Shared Utilities\Bitbridge.exe
An error occurred whilte trying to replace the existing file:
DeleteFile failed: code 5.
Access is denied.

Should I just ignore, or is there perhaps a deeper issue...?

Try running it as an administrator. Right click on the icon of it to do that. 

John
Try running it as an administrator. Right click on the icon of it to do that. 

run command center as administrator?

Reboot your machine and make sure SONAR is not running before doing the update.