I learned English from Chinese English teachers. I have to admit that some of them are really knowledgeable, even the foreigners think they are just amazing at teaching and explaining--GRAMMAR. It's not a bad idea to learn the grammatical rules from a non-native speaker.
Even you try your best to expose to a rich language environment, no matter you learn from a native or non-native; as long as you don't practice, everything is just in vain.
Practising English with a native speaker doesn't work to everyone, but the truth lies in "practice makes perfect."
- For Teachers