Both Mixcoin (see https://bitcointalk.org/index.php?topic=423596.0) and CoinJoin (see https://bitcointalk.org/index.php?topic=279249.0) are designed to address the transaction graph problem, where linking a transaction to one participant's identity can end up revealing all of that participant's transactions.

My question is: which of these two approaches is easier to implement (on top of, or in parallel with, Bitcoin or an altcoin)?