As far as I can make sense out of things 1.7 won't ever see the light of day and is just a deflection exercise. There is no point in ordinary users abandoning the stable release of 1.6.3 because there's nothing significant in the 1.7 even as it was proposed back in February (almost last year) The whole thing seems to have been the promise of a buggy, very little? See... http://www.question2answer.org/qa/31514/what-do-you-want-in-question2answer-1-7
I note that the only reference to any kind of roadmap, including what 1.8 might deliver has been erased form the posting, so. The future doesn't hold out much hope and who knows if/when v1.8 will see even an alpha release... No doubt it will be soon?
What advantages do PHP 5.5 or mysqli over previous iterations mean to users of Q2A and all they effectively gain is a pile of bugs in somebody else's playground.
Yes, I know the difference between alpha, beta, RC and stable releases and the jump from 1.6.3 to 1.7 should have delivered something for users. Representing quite a major release but instead, it is a glorified 1.6.4 beta at best imo.