I prefer the regular PB Freddy fenders which only have one stay front and back because they look cleaner. Never had any rattle issues. And I've used the rears on two polo bikes. The one got the fender folded up under itself from a collision,I just popped it back in place and bent the stays straight.

I've had zero issues with fenders,I just make sure the stays are properly tensioned,and use blue Loctite on all the bolts.

Edit: how tight is the mount at the fork crown? On one bike,I did need to install a bit of rubber into the fender mount's slot to prevent side-to-side movement. I used a rubber Schrader-to-Presta hole grommet. If the mount at the crown isn't tight,the fender will be able to wobble no matter how tight the struts are.