I will bump up this thread when I get around to ordering one. The quart sized zip-lock baggies are thicker plastic than any of the sandwich baggies I've tried. So, while it does need to be folded more it actually lasts longer for me.

Supposedly, the small Seal Line bag is 4"x6" and photos show an iPhone being a (somewhat close) fit. My cell phone is smaller, so I'm not too worried about things fitting inside the bag--I'm more worried as to how it'll fit in different jersey pockets. However, if I can't use it on the bike it'll still get used.

How large does the bag you have for kayaking actually measure, by the way?