Yes, if they have 4 bolt mounts or Vee mounts it creates a "stress riser", which is basically a point where all the flexing forces going through the fork are concentrated on, so they will normally crack there Think about the old T-Pro frames, the 04-07 ones. The gusset connecting the headtube and the downtube had a closed end, so all the forces were concentrated on the point of the gusset, so nearly all of them that cracked went there. I've got 07 Controls, which I think are just about the lightest fork out apart from Dobs, and the flex in them is really noticeable even for me, I rode down a hill recently and braked really hard on the front brake a few times, and I could see the fork flexing backwards by about 30-40mm at a guess. Apparantly the TrialTech forks are super strong, bit pricy but it'd be worth it if you couldn't break them.