I've heard many people say they've worn them on a long hikes or backpacks and found them to be great, but I haven't been able to. For me, the straps start to rub and the foot bed starts to feel hard and on smooth river rock, you lack even basic ankle support.

I think if you were to find a good, inexpensive pair of tennis shoes, you would find those suitable to occasional canyoneering trips. Try to find a way to track sales on past year inventory at rental stores in Springdale UT like Zion Adventure Co, you can snag gear those shoes that way (might be very well used though).