Your $regexex can be easily scripted but to implement in mIRC i personally don't see the use because how would it react when you have more then 1 capture ?
Perhaps the same as \a does in substitution...
Also just returning the first match is useful too, like $ifmatch returns the first expression of an if statement but ignores the rest, that is still fantastically useful. If it were necessary to reference all parts of an if then we would have more than $v1 and $v2, there would be $v3 to $vN.
