Some time ago I realized work was a bit faster if I could enter passwords with just one hand. Then the other hand never leaves the mouse. I started using the set [1-6,qwertasdfgzxcvb, caps, shift] - essentially what the left hand reached.
Letters and numbers, shift and caps being allowed, this didn't reduce security. This can be done with the standalone version of PasswordMaker, but the extension for firefox appears to have hardcoded [a-z,0-9].
It would be slick if the Firefox extension allowed differing letter/number groups.
I realize that the intent of the program is to autoPaste, but there are still times when one needs or wants to enter by hand. And Firefox has been known to suddenly lose all its extensions and settings.