The thing is though, for your average road use they'll probably never be a real problem I wouldn't have thought. Unless you're really pushing it on track then they might have issues.
I agree, but for many modifications are a way of life, badge of honour, even if they are not really necessary.... It's the owners car, so as long as the mods arelegal, why not.
If you take a standard car on track, the best modification you can do is upgrade the brake fluid from Dot 4 to Dot 5.
Once you get too much heat into the discs via the pads and calipers you can start to boil regular Dot 4, the Dot 5 has a higher boiling point. The boiling of fluid is apparent by a softer brake pedal and less braking efficiency.
The downside to Dot 5 is it is more hygroscopic (absords moisture), so the service interval is sooner and costs more than Dot4.
The other issue with heat is the less pad material you have remaining, the less effective this is at dissipating heat, so this adds to the potential problems.
A PP/R/Cs/CSS braking system with enough metal and compound on the pads should be fine on UK roads even with spirited driving, it's only when you get below, say, 25% remaining life, does the heat issue suddenly become more of a potential issue.
Of course there will be heroes out there who can ruin a set of discs and pads before they get to the end of their road?
