You can now deposit and trade MSAFE coins on MasterXChange:
https://masterxchange.com/market.php?currency=maidAs I understand it, they are not doing withdrawals yet (out of caution until they are happy with their security model).
Regarding tainted coins, I do NOT speak for Maidsafe, but speaking for myself, I support complete bitcoin fungibility, and the Master Protocol was written with that as an underlying axiom. Our distributed exchange allows you to sell Mastercoins for bitcoins without using an exchange website at all, but it gives you no ability to discriminate between bitcoins. The lack of a trusted third party means that third party cannot lose your coins to theft or idiocy, and they also cannot seize your coins if they do not like their history. Anybody selling Mastercoins on the distributed exchange today is also accepting the axiom that one bitcoin is as good as another, regardless of where it came from.
If I were running a crowdsale, I wouldn't care if 100% of the bitcoins I received were "tainted" because the protocol assumes one bitcoin is as good as another. If you ran a convenience store and somebody told you the cash in your till had been tainted by some criminal act in the past, what would you do? Nothing of course. You'd be hard pressed to find a dollar in circulation that wasn't tainted in some way. Dollars are fungible. Bitcoins are fungible. Stolen bitcoins are GONE, and the only way you'll get them back is through the kindness of a stranger who feels sorry for you.
So all this nonsense about where the MSAFE coins came from is a bunch of noise. One bitcoin is as good as another!
Again, Maidsafe may completely disagree with this position. I speak only for myself (and for the principles of the Mastercoin Protocol I designed).