I think what John was getting at is, the Admiral trans still turns the inside tires (at 1/3 rate in high gear) when in a turn. The t-20 in a turn first disconnects power to the inside wheels, then applies brakes to them depending on how far the stick is pulled back. The drawback to the Admiral is that it cannot do tight turns (spin in place) without shifting to low gear. In low gear it turns the inside tires backwards (counter-rotation) at 1/3 the rate of the outside tires. I really wouldn't call this an advantage or disadvantage....just different.
I've heard the high/low gear vs single speed argument before, and don't agree. We all have variable gear ratio through our CVT clutches. If that isn't enough, you need MORE HORSEPOWER. ....does anyone ever complain that their motor has too much?