Having packaged up two sets of brakes I can confirm that Vrs 312mm complete setup weighs 27.8kg once boxed, 256 rears weigh 15.6. So that's potentially 43.4kg removable!! Who needs brakes anyway?

Last pic

http://www.briskoda.net/forums/topic/238264-j0hns-bbt-hybrid-k03-mk2-octavia-whats-in-the-box/?p=3634026

Engine braking all the way

Even lighter if you take the engine out  

Joking aside, there is a lot to be gained by reducing the unsprung mass of a car. It totally transforms the handling characteristics of the car with less unsprung mass.

This is true. My current 6 pot brakes are quite light fir their size. The calipers themselves are a very good weight for the size.

Big hole in the floor removes even more weight, & you can stop Flintstone style

I seem to recall someone on here saying that the size of the brakes makes no diffrence to the braking ability so why not run 10mm discs with mini calipers...save weight and it wont effect the braking

To a certain extent that's true too, the only advantage from bigger discs is that the larger surface area means they can cool more quickly.

It all helps.   My front Hi Spec calipers weigh 900g. each bit different to the 2.5kilo Ford M16's I took off.  The lighter the car the more you notice small weight reductions.