maybe I have think it too simple.
for the vote DAC, open a vote thread, or vote for a thread, both need fees to protect the network security I think?
from the other hand, the vote fees will reduce the motivation.
yes the award can give some extra motivation. and the award should not be very big, this will attract the speculators.
for example:
the fee is 0.1, and 1000 vote win finally, the award should less than 0.1*1000 = 100.
the idea is just want to encourage the guys who really want to vote, not the speculators.