Holy Thread Dredge, Batman!
I'm going to say that balanced wheels are more important the faster the wheel spins. At off road speeds, they just roll around at the bottom of the tire. Washboard roads - Hmm.. How fast do you fly over them? I don't think beads are going to smooth out the washboard roads.
FWIW - I ran the dyanbeads in 35s. Not sure they added life to the tire, but they "probably" helped the ride overall.
Having done the beads, I would just go grab some airsoft ammo next time.