I've run my 441s and 576s many times in a downpour doing storm cleanup. The only problem I had was when I dunked the 441 in a swollen ditch while cutting a tree off somebody's house. But that would kill a standard carbed saw.Nothing is truly waterproof, but Autotune and M-Tronic are very water-resistant.
I don't really think companies like Husqvarna and Stihl will hire engineers who won't weatherproof their products. Sure, they might have other bugs. But I doubt they would ever do something like that.