Might I suggest making legacy & limited edition skins permanently available in the beta server? People who have them on the normal server wouldn't be any less special, since they'd still be the only ones who really own the skins, while having them available in the beta would not only allow everyone to use them (somewhere it doesn't matter), but also make it easier to test whether new updates introduce any bugs (currently, you have to wait for someone who owns the skin to use it AND for the right circumstances to trigger any bugs). Then again, people who actually own them likely wouldn't like it if everyone could get them, even if it was only in the beta server where it doesn't matter.
Also, I want Kitty Cat Katarina. -.-