I think they implemented the stop'n'swop functionality on the xbox live arcade versions, did they not?
I must admit I also clicked the link expecting something to do with eggs and crystal keys.
I'm so glad somebody else remembers that.
It was years after the game came out, and was perhaps just a side-note in the videogames magazines, meaning that nobody believed my childhood self when I claimed to finally obtain the eggs.
FYI a spiritual successor to B-K appears to be in very early stages of development. https://twitter.com/MingyJongo
I still checked for years. In fact if anyone is interested in the full breakdown: