Put it to you like this, Spanky. You want to see if McCown is the QB of our future, and are willing to stand pat at that position until you see, right? In that case, we'll either be set at the position for years to come, if he pans out, or our team will most certainly be mired in ineptitude once again for roughly the next 3-5 years.
I know you're probably going to argue the last point, but you'll be wrong. If you decide a young QB is your man, you have to give him a chance. That's at least 1 season in some cases, but if you've decided he's your franchise QB, then you have to give him at least 2. Then look at our track record. As long as he shows any kind of flash, hell get at least another season or two to 'develop'. If he sucks, we won't get rid of him until well after we should have.
So. You may be willing to just roll the dice over the next few years like that, but I am not. You can never have too many good QBs. Draft Manning or the Miami fellow, and let the best QB win out. If That's the 1st rounder, then fine, you spent a 3rd rounder on possibly a real qaulity backup QB (which is VERY important), or you can even trade him, if he looks to be a star, for up to a 1st rounder.