The Mycra Pac is lovely but is only water resistant and not actually waterproof with taped seams. Plus the 2-button closure doesn't do much in the wind. LLBean's H2Off line has taped seams and waterproof fabric but can be a bit noisy to wear depending on your movement and if that sort of thing bothers you. If water repellant is OK and don't need 100% waterproof there are more options even at Uniqlo
I checked Uniglo after learning of the brand here
Saw a very cute jacket but I don't think it's going to meet my "mash it in a bag" requirement. Whatever I end up getting will receive a waterproofing treatment on top of whatever it claims to have. If I could make a jacket out of my cheap, fold-up duffel (the one for all my travel purchases, lol, that was meant for one trip but looks like new after a dozen times being checked) I would
Thanks for the suggestions!