I have used mine in 40+ mph gusts before with my CM3s and they performed beautifully, so I'm quite surprised at beatkilla's bad experience.
beatkilla - One thing I noticed you mentioned in
this reply to that Gov't Mule is that you had no space at the end of the caps. You typically need a couple cm space of "dead air" for windscreens of this type to work correctly. If you pull them out to allow for this space, does the rubber ring no longer go past the rear vents? If it's not covering, you might need the next size up.
jbell may have a point that hypers in heavy wind may not be the best choice, but then again pro ENG people use shotguns in heavy wind all the time. They usually have a full-out Rycote Blimp for those situations, however. Look at all the empty space around the capsule in one of those!