Aqua stealth may be ok for wet rocks at the landings, and fine for wading boots, but how is it going to perform on muddy portages?

IF the new sole will have good cleats, then I'd say you have nothiing to lose - BUT, if the new sole is going to be smooth, like the felt bottoms of wading boots, then I'd think it would be a poor choice fou use on the protage trails.  You will have no traction in the mud, or on loose soil and duff.  Regular climbing shoes are terrible on anything but rock, because of that smooth sole - with a few loose pine needles on the ground, or dry and dusty terrain, climbing shoes always slip.

I have had two pairs of Rockport walking shoes that were fine to start out with, but become extremely dangerous to walk with after the soles wore down smooth - one drop of water under them and its like walking on wet ice, even on nearly dry sidewalks - its not teh material itself so much, as it is the very smoothe sole.  

Before you spend the money, find out what the sole will look like - if it is a amooth bottom, or with shallow siped cleats - no point in trading off a bit more traction in the water at the landings for less traction on the portages.