Car performance is all a matter of balance. The harder it goes, the harder you need to be able to stop. This increased stoping power comes at a price, & that seems to be increased mass. It's hardly worth using the big Commodore calipers on the large Magna discs & mount them to 200B struts if you are running a near stock A14 in your grocery getter.
The braking performance would be supurb, but the vehicle performance just wouldn't warrant it.

Obviously the opposite situation of using a CA18DET with original drums in racetrack competition is more than just a little silly, but using a brake system that is right for the rest of the car is the way to go. so figure out what the car is to be used for & work with that.
IE. Road cars usually travel slower than race cars & ride quality is more important, so a lighter brake/suspension could be justified & I suspect that with an A15, the B310 [Sunny] struts & brakes would be needed for engineer certification. These struts will still take the 1200 shock inserts & springs, so it sounds like a good choice to me.
It's all a matter of balance.