I think you'll find that most motor factors now pride themselves on selling either OEM parts, or parts from reputable manufacturers, rather than cheapo pattern parts, as was common not too many years ago.
I have yet to buy brake parts from a motor factors that weren't good quality, but then I'm careful about which factors I use.
Ironically, in some cases (aparently GM / Vauxhaull are very bad for this) a motor factor will sell OEM parts, but the dealerships are selling cheaper pattern parts. They fit, and are allegedly to specification, but are not OEM, and are usually not as good quality.
I find my ZX brakes are ok.. I can easily lock both front wheels if I brake hard..
I put the calipers from a Volcane on, new-larger master cylinder, and bought bigger vented disks, plus new shoes.. Its not bad at all now..
James. (Nr M67 East of Manchester).
Dark Blue ZX 1.9D Auto 1994 'L' 5 dr (modified) Aura. 98K miles used daily. Ave mpg 40
Wedgewood Blue 75 CTD auto Connoissaur. 2002. 144k. used daily. ave mpg 40 ish.