Probably. Some booster packs have had the internal names for certain parts changed during the testing phase, usually as part of some bugfix. If you saved the costume before such a change, then the costume won't load afterwards, on Test or Live. But if there's no major changes between Test and Live, then yes, you can. You just have to move it from the Test folder to the Live one.
@Roderick
OK, thanks.
(Sometimes, I wish there could be a Dev thumbs up button for quality posts, because you pretty much nailed it.) -- Ghost Falcon
If I create a costume on the test server using the new Beast Pack parts, can I save it on my computer and then pull it up after I purchase the pack on the 23rd?
(Sometimes, I wish there could be a Dev thumbs up button for quality posts, because you pretty much nailed it.) -- Ghost Falcon