I did a little experimenting tonight. Here are a couple HSS shots. Yes, I know I sacrificed flash power. This gym is fairly well lit, I figured I could drop ISO, stop down and still get something usable.
First one is ISO 2000, f/3.5, 1/400, FEC +2
Second is ISO 2000, f/3.5, 1/500, FEC +2 2/3
I usually shoot ambient but on occasion need to use flash. I do like how the colors "pop".

