GPUs for defense - questionable

What we gain by using a GPU (wisely)
A lot of computing logic is put to use (beyond a CPU's)
Can install up to 8 GPUs per machine easier/cheaper
Many attackers also have GPUs and benefit from these same things, although most nodes in a botnet may be unsuitable
What we lose by using only a GPU
Potential for unfriendliness to attackers with primarily GPUs
Memory requirements for attack, unless we manage to use each GPU card's global memory almost fully
May combine use of GPUs with use of the host's RAM
by two distinct components of the hashing method
This addresses the drawbacks above, but adds complexity