I haven't used either cartridge; I used a Grado Z2+ or similar many years ago and loved it; the Gold stylus is its recommended replacement.
However, here are 3 user reviews for the AT440ML.
And here's a thread about the AT440MLa on Steve Hoffman's website: http://www.stevehoffman.tv/forums/archive/index.php/t-80334.html
You are familiar with the Grado Gold; maybe the AT440ML reviews will help you decide which performance parameters are more important to you.
However, here are 3 user reviews for the AT440ML.
And here's a thread about the AT440MLa on Steve Hoffman's website: http://www.stevehoffman.tv/forums/archive/index.php/t-80334.html
You are familiar with the Grado Gold; maybe the AT440ML reviews will help you decide which performance parameters are more important to you.