Listen to Gordon: the voice of age and experience! (Sorry Gordon, but true!).
Basics: Old engineer's saying: "When you have two cats sitting on the roof, which one falls off first? The cat with the smallest
Mu" or if you like, coeiffient of friction.
Friction is not dependant on Surface Area: it is dependant on the interrelationship between the two materials and their effective mass.
Thus with a given
Mu, what varies in a braking system is
Pressure!
So why do larger tyres promote more adhesion? Why do larger disks/drums and pads/linings promote greater retardation?
Heat Dispersal!
Additionally, with tyres, a larger surface area allows a larger "Footprint" which allows less "Tread Shuffle", which allows greater faster heat dispersal. Heat in tyres is generated by the cords rubbing and twisting. less tread distortion, less heat.
If you change brake pads to a far "harder" pad, predal pressures increase, rapidly. Obvious.
Old pads used to suffer from "fade": a few hard applications and they burnt out: fun when approaching corners much rapidly!
Larger pad area and a greater friction coefficient means less "fade". It also means greater pedal pressure.
Small disks and small pads would be fine, if you can arrange to dissipate the heat quickly enough, which is usually pretty hard. Too much heat means spot hardening (very much so with cast iron) and grabbing and eventually failure.
Ventilated disks obviously assist in throwing off heat: but also incude inherrant weakness due to different rates of metal hardening and thus earlier failure. Same with cross-drilling.
Early experiences
with my sparkling new Ford GT Cortina in 1966, running cross-ply tyres - which were standard in those days! - showed some of the problems!
In the wet, one disk would throw the surface water more quickly: leading to sudden grabbing! Add with aquaplaning from the captive layer of water at the tyre's leading edge, thereafter, all sorts of jollys took place!
The cure (Service Fix; oh dear how Henry loved these 'cos they were cheap!), was to cut two cross-grooves in the pads with two hacksaw blades held together in the saw frame!
Also, shifting the calipers to the back of the strut helped even more. (Ford had switched caliper position from the back to the front a la Lotus Cortina to aid cooling).
If you want greater cooling, then fit larger diameter disks; and thicker disks; and bigger calipers!
Don't drill!