Turing completeness is a horrible idea for scripting in a cryptocurrency. Just look at the past couple of decades of vulnerabilities in java, javascript, flash, etc, etc. Turing complete money will drain your wallet on it's own.
The only thing I can see stopping it is another cryptocurrency which accomplishes everything that Bitcoin does and more, only with a codebase so different that Bitcoin can not adopt these added desirable features.
May I ask how important you feel Turing completeness is in the scripting language?
I'm sorry, I do not have the technical knowledge to answer this question. Give me a few days and I may be able to give you an answer.
+1
These are good points too. Turing completeness in a scripting language means that "anything computable, can be computed by running the appropriate script." So there is an infinite surface of potential problems that would slowly show themselves, I think. The Java exploits are a good analogy.
just think about something like
{ while true; }
in the scripting language. I send you such a transaction. Will your machine lock up in an endless loop?
No comment on weather this is a good idea or not, but theres a simple solution to this particular problem: fees.
Only execute the first x operations, where x=fee*const. Sure, you could make a machine freeze up for a half a second, but you'd be paying out the ass to do it.