Originally Posted by D_o_S
Now, in order to "blip" the throttle, I must take my foot off the brake (hence transferring weight back to the rear, relatively) and press the accelerator
Since you're posting in a track forum, the answer is you need to start learning heel-toe today.
About double-clutching, if I downshift from high speed into 2nd without double-clutching, I feel pretty strong resistance in the gearbox. I've been told that forcing the shifter past that resistance wears the synchros more quickly. In any case, it feels much better if I do double-clutch, and since I'm braking simultaneously anyway, there is no downside.
As for other gears, I don't think I ever feel resistance downshifting into 4th or 3rd in this car, but I did sometimes double-clutch into 3rd in my last car, which was a Mazda RX-8. And I rarely downshift into 1st, but if I do, in a parking lot or something, I always double-clutch.