Balance point is a personal thing. I'll check a few Shureido sai when I get home and report back. I've used standard small, medium, and large Shureido sai, and find the small size have the best balance out of the box.

I've also a pair of medium Shureido sai with thinner shafts that I special ordered from Shureido Okinawa. Other than these sai, my "go to" Shureido sai are medium size carbon steel with a black coating. I removed a bit off the tip, tweaked the yoku and shortened the tsuka to size, and had a different butt welded on. After that, I filed down each of the flats of the shaft until I had the balance that suits me best, then applied gun blue. Expensive Sai when you consider my time...even at minimum wage...