If the efficiency of GPU mining is 10 or even 100 times that of CPU, with GPU miners in the hands of only a few, then we essentially have a bad ICO instead of a fair launch.
Despite fairness concerns, which can be relative anyway, and despite the greedy vibe that this community would give off from day one, there are two more issues i can think of:
- It would be easy and cheap for a group of individuals that might not be so happy with the upcoming launch of zcash (btc, monero, dash whales?), to buy the gpu miner and 51% attack zcash at launch. It has happened before.
- Malicious fake gpu-miners will flood the forums, twitter etc. targeting wallets or pushing ransomware.