This isn't really a problem, just an a-ha moment that I had. I have the Canon 135mm f/2 L, which is non-IS. I also shoot with a Canon 5DmkII, max shutter speed sync of 1/200 sec. I also have a non-HSS flash. When I was combining all three the other day (combining flash with ambient), I realized that I need to keep my shutter speed at least ~1/160 but under 1/200. That's not a lot of wiggle room.
Not a complaint, just an observation. I won't be able to get the HSS for awhile, but you can bet its next on my wish list.
We now return you to your regularly scheduled forum.