Hi Mac- So, have you found something light and waterproof that is also more compact than the Propore jacket? 

No.  Patagonia did a jacket (or maybe it was a pullover) a few years ago that I remember being interested in for its compact size.  I remember them describing it as being about the size of a Cliff Bar when it was rolled up.  I had always assumed that this referred to a size small, and that by the time I got one big enough to encase my Sasquatch-esque bulk, I'd end up with something more the size of a mt. bike inner-tube.    I'm not sure if that jacket was ever supposed to have been waterPROOF, though--just highly water resistant.  But since I have yet to find a jacket that keeps me completely dry on a hard ride in prolonged rain, I've long been willing to settle for good-enough.

My problem is that I have a cycling rain jacket that's OK.  It's not great, it's not particularly light, and it certainly doesn't carry very compactly, but it's good enough that I have yet to feel like I can justify buying a replacement for it. 

mac