I will just add that 14' boat is too big at low water...unless you are determined and know the lines, and are willing to get un-stuck.
the box gets much more tricky for rafts at low water. lots of rock dodging and pretty mandatory slots to fit rubber boats through. 11' R-4 would be much better plan for low water.
>above 900 cfs take whatever craft you want, but be wary of low flows
17 miles, sheer canyon with little river traffic, so pack expedition style.
IMO powerline and pinball/rockgarden/Rio Bravo are the ones to take seriously. (basically the next 2-3mile section after powerline)
also there is a bad sieve at the bottom right of rockgarden.
"Just left of Center"