Steve, I'm sorry if you think I have misinterpreted you, but your initial post on this subject did very explicitly state that, 'leaf shutters have a built in delay (for electronic flash - X-sync) to time the flash to compensate somewhat for the shutter not being completely open when the flash is triggered'. This is simply untrue, because the way that leaf shutters work means that the blades are always fully open when the flash is triggered.
You went on to say that, 'the faster the shutter speed you are using with a flash, the greater the exposure problem...' Well, this is true, but only because the flash may be too long in duration for the open time of the shutter. It has nothing at all to do with the acceleration/deceleration times of the shutter blades. It would be true even if they could open or close instantaneously, and in fact the problem would be worse if that were the case.
You also said, 'the larger the shutter, the greater the problem because of greater mass, etc.'. I'm sorry, but no. Large shutters do indeed take longer to open and close, and this is why, for example, Copal #3 shutters have 1/125th as their fastest speed. But it does not affect flash sync.
Finally you said, 'my advice is to expose at 1/60th second or less using an electronic flash with a leaf shutter'. I'm sorry if it upsets you but I think this is bad advice, and it is the main reason I posted a follow-up. Only when using very high flash powers is it necessay to use slower shutter speeds, and that only for the reasons stated earlier, and it would be true regardless of what type of shutter was in use. For most handheld units you can safely use shutter speeds up to 1/500th with leaf shutters almost all the time, without any danger of the shutter itself cutting off the flash before it is fully discharged. For a few handheld units and for studio flash at higher power settings it may be necessary to stick to shutter speeds of 1/250th or possibly 1/125th and slower. To use speeds of 1/60th or slower whenever using flash is quite unnecessary, and squanders one of the main advantages of leaf shutters.