The Valor, Knight and caliber share essentially the same driver and amplifier platform. Their overall output is relatively close, with a slight advantage going to the Knight and Caliber over the Valor. However, the Valor still has a lot of overall output and slam thanks to that very capable and efficient 15 inch driver.
The big difference is the amount of output in the 20 Hz and below region. As you move up from the Valor to the Conquest, you are getting more extreme low frequency output capabilities.
The Knight has about one and a half times the output of a Valor @ 20 Hz. The Caliber has almost as much output as a pair of Valor's @ 20 Hz as well as a noticable advantage over the Knight in the 15 Hz region.
The tradeoff is size. The Caliber is about twice as large as the Valor. That change in cabinet size allows for some pretty big advantages in 20 Hz and lower region. They are all very capable, but the larger cabinets allow the driver to deliver more low end output.
Even so, as several others have mentioned here, the Valor is one heck of a performer.