I didn't think a1ex was keen on changing properties.
From what I have read, the guys trying to flash illuminate birds from 13klms away (yes an exaggeration), use a snoot with a reflective inside. This has the advantage of increasing the zoom factor of the flash and giving you a higher GN. Enough flash light on subject will help with the stopping power.
I've personally never had problems with motion @ 1/160, but I always have enough stopping power with flash.
If you're trying to flash illuminate running horses 10klms away with an 8mm focal length (yes another exaggeration

), you should really think about other means though.
I can't see how increasing the sync speed to 1/180 while retaining 1/3rd stop FEC is going to net you more keepers.
If you have enough power to FEC, half a stop isn't that large. Best case, 1/3rd stop FEC is only ever going to be at most 0.25EV more accurate then 1/2 stop, best case. If the flash exposure is anything other then at that 1/3rd stop exactly, the accuracy becomes even less.
I'm just being difficult as usual though
