Thanks for the notice about that tool. I have been keeping empty older-version gdbs around for the same purpose but I like the tool.
But, I just made a 10.0 gdb and mosaic dataset from my 10.2 install and another 10.0 machine can't read the mosaic dataset. Should it or am I expecting the tool to do something it can't?
Your frustrations will grow when you go to publish a mosaic dataset using AGS, only to find that the Image extension is required.