In the updated OP it now says 1000XC is the requirement for trustless mixing all the time. Is this final?
1000 XC for xnode do make sense because you will earn XC if run as a xnode.
Yup, it's 1000 XC.
This amount is still somewhat provisional.
Also, if XC's value increases, it's very likely that the required balance will decrease.
Mining since 01.06.2014 on btc multipools, buying up all the xc I can and got 550 2 days ago, was quite happy, until now...
This makes me a sad panda