I've been racing on FCR plain discs and RA pads for 2 seasons and mine have been perfect. No cracks etc and that was on OEM calipers. The discs have lasted over 1 year but the pads wear quickly. My pads wear down to near zero without cracking.

If your tyres are shot the that massively affects braking distances and therefore the duration you are on the brakes.

The RA pads are more aggressive so you may find they do the trick.