Well I can tell you that the concept itself is really really fun, based on what happened in the secret santa event. People secretly made characters for each other and went to deliver gifts with others. The character I got was pretty damn amazing (LONG LIVE TINKLES MCCRINKLE) and I had an even more amazing partner.
So yes, the concept can work if done well. What would be the setting of the RP though? Pokémon, modern, futuristic, fantasy?
I think me suggesting a similar concept helped inspire Secret Santa. I did make a character for that event, though I never ended up posting in-character.
I said the setting would be an everyday, modern city wrapped in fog with no ties to any pre-established franchise or universe. I wouldn't want to limit the roleplay in that regard. Though, now that you mention it, what if Changeover took a page from Secret Santa's book and allowed a multitude of characters from a multitude of universes to collaborate together? I think that could work interestingly in terms of an incorporating plot and setting.