I think it's really splitting hairs in context of design and fashion. It's my opinion that the two functions should look and breath similarly, with their only difference being the way in which either function evaluates its substitution text, and NOT in the parameters which they use. That way, you can alternate between one and the other, in practice and use, without having to refer to the help file to figure out how their parameters differentiate -- because they'd be the same parameters.
This goes in line with $replace() vs $replaceEx(). And so too $regsub() and $regsubEx().
It is pretty normal for mIRC string functions to return Text or Number depending on the parameters provided to the function. I'm not really sure where the apprehension is coming from in this regard.
"Performs a regular expression match, like $regex(), and then performs a substitution using subtext. If an optional variable is supplied as the last parameter, the text will be stored in that variable and the functions will return the number of substitutions made to the string, if any."
