An update on this.
The iOS 8 release date has been officially announced for Wednesday 17 September, one week from now. Apple has released the full iOS 8 build through the developer programme, so we're now not only testing on the final build but we're also testing a version of our app that's been compiled with the new version of XCode, to see if there are any more compatibility fixes we need to make.
We've already got one build in review with Apple, which contains a tonne of compatibility fixes for iOS 8, but is fully backwards compatible with iOS 6 and 7. If that's approved, we'll immediately release it. We're spending the rest of the week working on supplementary fixes and we're hoping to submit another build soon.
Thanks,
Dan