I still don't quite understand how this can occur. By necessity, LV3 (as you call it) requires a total wipe of the phone, completely replacing everything on it with the new OS. It shouldn't introduce the same bugs that an upgrade process would, and only those in the new OS itself, since there's nothing else there.
How does a factory reset make a difference? And is this the same as clearing the cache? (As mentioned by thenestor)? Is there some trace data that survives the "clean install" process that we've been doing on the leaks?
Since I am noticing issues that I never did on previous leaks, I know it's not hardware in my case - unless I just happened to break my phone the same day I installed LV3. If the problems persist I'll probably wind up doing one or the other of these, I'd just like to be sure of WHY I'm doing it... thanks