So far, I've tried new ProGrips 719 grips, Grip Puppies, and filled the bars with lead shot. I did not use silicone with the lead b/c I'm not sure what silicone to use that would not be so sticky I could pour it into the bar.
I'm going to try the fz1 bars next, for less sweep and a different angle on my wrists. All the mods so far seem to help, but the vibration is still there, most noticeable b/t 5-6000 rpm, and it only bothers my throttle hand. It seems like maybe a steel throttle tube would be better than plastic, but I don't know.
At least now I can shake it out easily, before my whole hand would just go numb. I might try syncing the carbs as well, but at this point I'm pretty much feeling like I can live with it as is. It's now no worse than any dirt bike I've ever had.