For the LCLS, the ML oscillator could have a longer cavity an lower repetition rate. This would simplify the design of the pulse selection system. The laser wire could operate at lower power, but the signal to noise improves as the power is increased. These are available commercially from several vendors. For the NLC and Laser Wire this must be a very short cavity oscillator to allow operate at 714Mhz.
Chirped mirrors are a relatively new technology, but are becoming more widely used.
Higher peak powers increase the non-linear focussing in the crystal, resulting in a smaller mode size and better coupling to the pump beam. The result is that high peak powers are enhanced, resulting in passive mode-locking. This works, but has the disadvantage of requiring the loop bandwidth to be less than about one kilohertz. This should allow much high bandwidths, and lower timing jitter. Note that this is required for the LCLS and Laser Wire, but not for the NLC source laser.