Actually, right and wrong... I did bring the 8wt top and stick it into the 9wt bottom to see if I could fish... and the answer was "NOT!" The top snapped just above the ferrule. The other DS I brought in for repairs (two needed repair last year) was due to a clouser encounter.
As for the cast.... I am sure everyone is wondering how well it casted at that length. It was due to a special cast I invented called the "spiral dump".
It works with any line, any weight, any time as long as you're on a boat or dock or something over water. You simply dump the line on the water in a coil and let the currentor boat drift pull it straight before you strip it back in