Yeahhhhhh - I posted this BEFORE exploring the app, but now with a little while poking around, I'm just gonna say:

NAILED IT!!!!

Addresses all my needs in one source. Easy filtering, integrated AW section descriptions, VERY good map view... FTW.

This just in:

https://www.americanwhitewater.org/content/Article/view/articleid/34043/

Fantastic! Exciting! Excellent!

While it's still very new, the reviews are strong - could be Just The Thing...