And one more comment on the Accushift 4050 Edge~
Last Autumn I loaned my bike to a local youngster for a 30 mile loop. It was his first experience with down tube shifters.
He showed some nervousness, and a bit puzzled. Told him to just keep his fingers clear of the front, pedal away and shift to whatever gear he desired, either or both at the same time, no worry of cross chain and all! The kid was digging it - lol.