The Jackson should go as dark as shade 14 and as light as shade 9, at least mine does. I looked at the Speedglas, and intended to purchase one, but the guys at the Welding Supply shop asked me to try the Jackson free of charge before I purchase one to see if it was what I was looking for. It seemed to work fine, so he sold me the Jackson and I left the more expensive one on the shelf.
Just a note, I've tried some cheaper ones sold at farm supply shops and such, don't be fooled by the cheap price, I didn't like the quality or the electronics.
A guy gave me some info on auto-darkening shields and I told him I would pass the info on and here is the link if anyone is interested.
(I do not have any experience with this shield, test it out on your own) http://www.usaweld.com/product_page/welding_helmets/9013060M.html
John Wright