There has been some debate over the ability of the xtfee/mining economy to function. You know, the whole tragedy of the commons thing.http://bitcointalk.org/index.php?topic=6284.0
If a solution is found, it may involve a drastic protocol change, which at this stage of bitcoin may be impossible. However, I believe I have come up with a way to bootstrap the new system off of bitcoin, sidestepping the whole get-currency-into-the-economy problem and allowing us to keep our hard earned value.
The idea is to spend bitcoins into the new currency (bettercoin). First generate a keypair in bettercoin. There will be a function F, which maps a bettercoin address, x, to a bitcoin address, F(x). The function isn't so important in implementation except that it's output must be a valid bitcoin address. F could be a hash or it could truncate the bettercoin address (if it's longer), flip the bits, whatever.
Now, in bitcoin, to transfer bitcoins to better coins you simply spend your bitcoins to F(x). As far as bitcoin is concerned, these coins are lost forever, because no one has the private key of F(x). This eliminates the possibility of double spends. Bettercoin systems have to read the bitcoin blockchain to check if coins have been spent to F(x). If so the bettercoin address x has the equivalent amount in bettercoins.
If bettercoin is indeed superior, all bitcoins will soon be spent into the new system in this fashion.