IMHO The rear disc brake conversion is pretty pointless unless you are racing, even then I could easily lock all wheels with standard brakes.
At speed the issue is traction for both accelerating and decelerating, not to mention road holding, and not the brakes.
Locking wheels is not a sign of braking efficiency in truth, but more a reflection on the feel and feedback available through the pedal to the driver. Really well setup brakes will allow accurate threshold braking - where you can hold the braking force accurately at just below the limit of grip - and the new rear disk conversion gets much, much closer to that setup than the drum in my view. I'm still trying to put good miles on mine (avoiding the storms as appropriate of course), but as far as I am concerned, the improvement in feel, feedback and braking power is considerable and a big step forward in regard to what I look for in a braking setup. I am putting an article together about my experience with the conversion and will share via the MTWC once complete. Good brakes are just as valid when making progress on the roads as they are in the heat of battle on track and the drum on the back is not there to aid performance, but just to make it cheaper to build unfortunately...
