I've only done it a few times in my Supras... The eight feet I have to move the shifter in between gears kinda makes me nervous about the whole thing. I can shift regularly just about as fast simply due to the distance involved, although you do loose more boost shifting normally that wasn't too big of a deal in my case because all three have been CT or upgraded CT cars.
In my Cobra on the other hand, my right foot doesn't move once it drops... Traction on the 1-2 and depending on my burnout and/or conditions the 2-3 shift can become a problem. It's noticeably faster than regular shifting in that car, but between the bump stops on my shifter and the ~5cm I actually have to move my hand there's basically no danger of me missing a gear.
In my Cobra on the other hand, my right foot doesn't move once it drops... Traction on the 1-2 and depending on my burnout and/or conditions the 2-3 shift can become a problem. It's noticeably faster than regular shifting in that car, but between the bump stops on my shifter and the ~5cm I actually have to move my hand there's basically no danger of me missing a gear.