+100000
Post up multi-sig block-chian proof please - I have had these concerns for a while.
Did you test for yourself?
Have you followed the developments made public in various XC discussions?
Added in edit:
The important thing IMHO to show is not that a transaction can't be followed superficially on the blockchain but that it is also immune from various strategies to identify transactions via other means than merely the addresses.
XC went through this long ago, and not only that, but XC had someone who really wanted to disprove it fail to do so, someone involved with DRK and who is quite bright.
Have any other privacy coins had this done?
Mammoth from what I understand has shown that it can obscure the path of transactions, but it was shown by those who wanted mammoth to succeed. This doesn't mean it doesn't work, but it's not quite as good IMHO
XC sure makes you guys scared hey...everything you want to know is in our thread, if you want to know read it, why should we do the work for you just to prove you wrong, we don't care....and there is a month old bounty still unclaimed for 2 BTC if you can connect the sender to receiver address, so go ahead knock yourselves out, cheplin from DRK did..it was extremely amusing he wanted that BTC but he...failed and gave up, now you can fail and give up while we all watch...have fun. 
Here are my most recent purchases. 
