Perhaps 7LM could help out with answers to your latest questions? :-\i
I have a scroll of paper upstairs, from a respected academic institution, that suggests I once knew about such things. But that was then and this is now. After a working life spent (miss spent?) in software development, i would be unable to speak with any confidence. That is why I generally try to express an opinion, rather than a fact.
Sometimes, believe it or not, I am sometimes even wrong. That is why I was inviting different views.
Must confess, I have just spent a few moments trying to dig up online technical material, but have found nothing I can cite to justify my suggestion that an ungrounded screen is worse than no screen. Various posts on various forums, some agreeing and some disagreeing, but nothing really authoritative.