Welcome back, conanite! I was coincidentally just thinking about you yesterday when I ran across your bug report at http://arclanguage.org/item?id=10485. Too bad that bug is still open in both Arc 3.1 and Anarki. I think I will try to fix it now that I've spotted it.
1. Thank you! I figured arc could have gone a lot further with special-syntax, by making it configurable inside arc code.
2. this "open source" has had only two eyeballs on it so far ... attacks welcome :)
3. The execution stack is entirely plagiarised from rainbow so it should not be hard to re-implement continuations in the same manner ... the need hasn't arisen yet though ...