Steve Vincent wrote:Nope

Not true. As long as you are comfortable with stopping the TM1 service and editing the affected cube file(s) directly in a hex editor then dimension names can be changed. Providing no mistakes in the number of characters in dimension names and as long as the new dimension matches the old dimension for all leaf elements where data is held then when the server is restarted no data will be lost and the cube will point to the new dimension(s).
How to do this is described here in this post
http://www.tm1forum.com/viewtopic.php?p=22780
Note: what you can't ever do without creating a new cube is to add or subtract dimensions from a cube.
Warning: this is essentially back door hacking and could be described as an "advanced" technique not for beginners and certainly not for the faint hearted. Anyone attempting this should back up the data directory first (kinda goes without saying).
A TM1 development tool that could facilitate doing this "automatically" via a GUI would be extremely useful IMO.
Hint, hint to those out there who are selling TM1 development tools, this would be a nice addition.