Well, I'll comment about this, especially since my name was mentioned twice.
I've run my 14 foot Hyside down there almost every year for the past 15 years or so. When I didn't it was because I used to run a 13-1/2 foot Riken for a couple of years, or I joined a trip that rented all the gear and I ran a 16 footer. Each time I wished I could have my 14'er instead! By the way, with my Riken people said that I looked like a bobbing cork in some waves.
To me, the 14 foot boat is no problem to row down there and it makes me feel more like I'm rowing a boat than if I had a larger boat. I can "feel" the river currents more and I have to read and run rapids with more care, sometimes with maneuvering, because the boat is more susceptible to large, rogue waves. But, it's much more enjoyable to me than a large barge simply pointed downriver and kept straight. It does take more analness to rig a fair share of the gear.
I remember a couple of trips I joined, in one case to get a group of Alaskans downriver and see the good hikes and such, but only if I got to row a 16 foot rental, not an 18 footer the rest of them had. That's just personal preference, not a comment on the usefulness of an 18 foot gear boat.
Anyway, I can still row into large waves and get a big ride (Sapphire!) because there is so much momentum in that river to push the boat's ass up and over the wave. The main thing is to watch out for a stopper wave/hole and a rogue wave coming from the side. (That's how I flipped in Indian Dick, going for a dance with that fuckin' right side lateral devil wave).
Bottom line, don't worry about rowing a 14 footer down there. It's great fun.