I've done considerable research into Xe flash lamps and concluded that for very high rep rates such as 10kHz and above, and very short pulse durations such as less than 1us and all the way down to sub 100ns, that they just aren't the answer.
Furthermore, there is jitter which would force us to use long camera gate times which would negate some of the advantages of operating at very high speeds, such as gating out background signal sources, and stop motion of very high velocity phenomina.
Additionally, lamps spew in all directions, which is also a problem with LEDs. But LEDs are closely related to laser diodes, so many of the drive electronics and experiments we set up with LEDs are quickly adaptable to laser diodes.
Finally, lamps are wide spectrum, so once you filter out a 20nm part of the spectrum comparable to a colored LED, you get not so much radiance anymore, and the LED looks pretty good. If light in the deep UV or near IR is needed however, lamps sometimes are a good choice.
I have a great deal of fondness for lamps, as I am at heart an "arcs and sparks" guy. But the LEDs are a great light source for some of my purposes, and superior to flash lamps in all of the cases which are driving my interest in LEDs.
Ultimately if we decide we want to spend more money on high rep-rate, short pulse sources, I will head back in the direction of lasers, though diode lasers, for cases where collimation/small apparent source size is needed.
The key thing I have to figure out with diode lasers is to accomplish de-coherence without loosing a large % of the photons.