:huh:
Chrono refers to a chronograph function 99% of the time. A chronometer is a watch that has been adjusted to run in certain accuracy parameters. All SMP's are chronometers, but only the ones with the chronograph function are referred to as "chronos".
The older SMP chrono reps are actually very close to the gen. They will take gen parts and the pearl out of the box is fairly decent. The three hand models of the SMP are off in several ways.
Here's on I used to have: