walky-talky recs?

Anyone tried any modern-style walky-talkies for use when fly-fishing
with (fast hiking) friends, ones that will work in river gorges? Or,
ever see any side-by-side reviews of such?

I just spent the last three days scrambling up and down river canyons
with friends, and could really have used a good pair to keep us in
touch. We almost lost one guy. My concern is that the walkys won't
work in the deeper gorge areas. Any thoughts?

Thanks, Tim