With scrypt variants this is less of an issue, with coins that have CPU mining only the reward for mining for the average Joe is very limited.
Considering SHA-3 should not be that hard to implement on GPU, are you not worried that CPU miners will be overrun by GPU miners (I guess that whoever writes the miner won't just disclose the source or even its existence) soon after start?
There is already working SHA-3 implementation as part of scrypt-jane miners, so ripping just sha-3 out of it ... wouldn't be probably very hard .
That is exactly what is going to happen. The happy-go-lucky crowd will be making 42 coins a day on their expensive i7-4700k and the GPU miners with their undisclosed mining software will be making 1.2 Million coins during the same day.
Im sorry to say this but there is so much openness and fairness built into Satoshi's implementation of bitcoin technology and continued over to Scrypt, that with the exception of pre-mining and insta-mining, every coin that uses some "innovative" technology (aka giving some secret advantage to the developer) has to be looked at carefully.