In my previous post, I forgot to mention that the base Focus strut mount could also be to blame by not evenly distributing the stresses from the strut bearing to the strut tower. So, I'll also be doing the ST top strut mount; I'm basically replacing the whole kit and kaboodle. It's a bit of a shot in the dark, but I'm also searching for a more performance-oriented suspension geometry (more camber, and maybe more caster), and the ST mounts are a different part.
Also, I have been searching c30world.com, mazda3forums.com and mazdaspeedforums.org to see if there's any similar issues between our cars and the Volvo/Mazda variants.
Ultimately, I've found that while some people have had strut bearing issues, it really doesn't seem to be as widespread an issue as with the Focus, nor is it an issue that many have from the factory. Some people have had premature bearing failures, but I've found that most people who do complain of strut bearing failure have altered their factory suspension with aftermarket components that they've installed themselves. zx3matt's girlfriend's car is an exception, though. I haven't really looked into the newer Skyactiv cars.
Joined the dark side.