You make a great case, Ramgator.
I watched himplay at Candlestick and knew... I'm in the presence of greatness. He could get hammered, get up in pain, and keep throwing. And as you said, he didn't lose his composure - ever.
It's one thing to stand in the pocket looking heroically statuesque, feet immobile, for five or six seconds with nobody coming at you, and find an open receiver. It's quite another to make the so-called off schedule throws that Montana did, or get hammered and get up and keep your composure and keep throwing. On that measure alone I'd have to rank Montana ahead of Brady on my all-time greatest list.
Without rules to protect the quarterback, some of which the NFL had to tailor for him, I think back to how well Brady would have done in Montana's 49er offense. He could have made all the throws from the pocket, granted; but he may not have been able to roll out as Montana did. When it comes to taking the licks that Montana did, Brady by no stretch of credulity could have. How he reacted to those hits is a matter of deceit and cowardice - not greatness.
Montana and Marino over Brady for sure - and you make a compelling case for Joe Cool, one of my all-time-great and favorite football players. In fact, you've got me thinking...