"txid" will be read by most programmers as "transaction identifier". And identifiers are used all over software, and no sane programmer would assume that they change randomly.
Of course you can go down the road of "WE DOCUMENTED THIS ON SOME WIKI" and pretend its not your fault then. But then you will see other people's software crash and burn over and over again. Really, which programmer would assume that an ID might change randomly? This is against very very common programming practice, and it is bound to trigger bugs.
