I understand not changing the regex engine for current reXXX functions and tags. What we could do is introduce new functions or a switch like this:
reFind( regex, string, [,start] [,returnsubex], [,regexEngine])
Where regexEngine is a new argument. This is inline with how the crypto functions work. It allows us to migrate from old tech to new tech for those who care. I think the supported engine should be java since that would be directly available and does not add any new dependencies.