Smallening the capacitors will not necessarily of necessity result in a shorter flash duration. My studio flash system at the moment consists of a few Elinchrom D-Lites (4s and a 2) and somehow a BX250Ri (which I don't use wireless as I don't know the specs for the Skyport wireless trigger system, otherwise I'd build my own transmitter for it) and the BX is theoretically quite a lot more powerful than the D-Lites, yet far shorter flash duration.
If I were doing the “freezing motion” sort of flash trickery, I'd probably try my Metz gear at it to get a very small duration. Picking up a few 45CL1s these days can be quite cheap, even if only for this sort of a project.