Yeah, what will really confuse you is autos with manual valve bodies! I've got a friend a hot rodded V8 in it, a 4000 RPM stall and a full manual valvebody etc... that car is ridiculous, but oh so cool.
But the advantages of those quick, perfect shifts and the nature of the torque converter makes for launches that you just cant emulate with a manual. A full manual valve body gives you those quick shifts and the almost traction control-esque properties of the torque converter without the danger/inconsistencies of trying to launch and shift a car with a manual transmission. Torque converters even soften the shock on the rear end gears and the rest of hte drivetrain, and it's actaully EASIER on them than with a manual, even though they're faster.
Personally, though, I always wanted a manual, and I've got a T56 going into my car since the 700r4's (same thing as the 4l60, 4l60e just has electronically-controlled instead of cable-controlled shift points.) are notoriously weak. A 4l60e built to the max can handle around 700 hp, over that and you're playing dice with Murphy. A slushbox is always going to be a hindrance at a real circuit, though, their advantages come through mostly at the launch.