I used to sell Maggies when I worked at a local HiFi shop. GREAT speaker! I don't know about their use in organs, though. Matching up a good sub to those things can be tricky.
They are also EXTREMELY unforgiving. You feed it a bad recording/sample, it will spit it out at you and make you wish you'd thought twice. Give it perfection, and it will reproduce perfection!
Plus, you dang near need an arc welder of an amp to power those things properly.
I do love them.