Exactly what Pat said. I would add that a poorly tillered bow is a bigger culprit of handshock than near-tip mass. Also, proper tuning and arrow selection play a big role as well. I've not noticed a difference in the four bows I've put brush nocks on compared to my other bows. Plus, they are the best, hands down, for their intended purpose: keeping brush from snagging between the string and limbs.
Thanks for the kind comments, all!