Just got an official reply from JVC that the split screen shouldn't be visible anymore or only lightly on +18 dB. If not I should return the cam. Any last concerns seem ironed out by that...

Was the reply in writing? Could you share it with us or provide more details, please?
Thanks.

It was, but it's in dutch so I guess it won't be of any use to you. Anyhow, that's pretty much what's in it.

Was that regarding to your camera or all cameras shipped from now on?

all camera's, because I'm still waiting on mine :-(

Well, me too and now I'm glad for not having mine yet!