I have a 'John Bailes', which is similar, and @!*%, it's fast. I have broken a frizzen spring once in a while, but I understand that's the norm with this thoroughbred lock. Keep a spare spring in your kit, one that has been fitted and tuned.
In comparing locks of similar size, one can get into a boondoggle of comparisons. A most important, and oft overlooked, factor is the polishing and fitting of the internals and hardening of the lockplate. A proper job can increase the lock speed tremendously, putting a Siler ahead of an Egg or Manton.