Hashrate is shown correctly when using Stratum on Coinotron, from my experience.
Then I'm clueless. Maybe is because I am still using the driver 11.12 and SDK from Catalyst 11.6, but I really don't feel like updating them.
Well, I'll mine Terracoins then, until someone gives me a good tip.
[EDIT]: it were the drivers: I updated to 13.10 and now it's all fine