double clutch downshifting is still easier on a car even if it has a synchronized gear-box. think of the clutch (wear), and think of the synchros. synchros wear out too! not to mention that the act of downshifting for power or a quick burst of speed is negated if you just drag the clutch against the new gear, thereby slowing the car down. if you are going to take the time to rev-match (heel and toe while braking, which i cant do right, or even just to get into the powerband) you might as well double-clutch because it wastes no time in that situation.

downshifting while maintaining speed, without matching revs, puts a lot of strain on the belts too: if they aren't tight enough this is an easy way to find out: it makes a horrendous noise. thats what i was saying, originally.

double-clutch downshifting is cool anyways because Gino Torretta said he does it all the time in F&F, especially when drag-racing, and anyone who double-clutches it on an upshift in a drag race obviously knows a LOT more about cars than you, anyway SO THARE.