Hey up Ste., enjoy the football tonight?
I did a quick search on OtsUsers and came up with
this thread.
Basically, to batch convert Ots files back to MP3 you need to use Ots Studio:
Import all the Ots files (File - Import - "Ots/Wave/MPEG File(s)"
Add all your Ots files
Click the Import button.
When done:
File - Export - As MP3 Files.
I've no tested this so don't quote me!