From what I can find on Google, it seems that Exo-Grid is only water-resistant, not waterproof. So it'd make a good windshield but anything more than a drizzle and you'll get soaked.

It's not true that nothing beats Gore-Tex. Gore-Tex has the brand name power but eVent, for example, is 50% more breathable than Gore-Tex, with comparable pricing. It hasn't managed to penetrate the market much but there do exist eVent cycling jackets.