There is nothing unstable about 1.7.18, I'm not sure where you heard that. however, it's not true. The biggest difference between 1.7.17 and 1.7.18 are a few tweaks and several bug fixes over 1.7.17. 1.7.18 has a few known issues with the mysql code, but those issues aren't any worse than those in 1.7.17.