I'm guessing your audiologist doesn't ride crits. Yeah, the sweat can be an issue. Although you can purchase hearing aid sweatbands that work fairly well. http://hearingaidsweatband.com/

They are, however, not fool proof. You can still overwhelm their ability to keep you aids dry. Personally, all four sets of aids I've had over the years were all bad when it comes to wind noise. I could hear lost of whoosh, and little else when wearing them. I think the only way you'll know it to try them. Although I'm not sure I'd do that during a race. Hope you get it figured out in a way that works for you.