My pioneer 427XD does have retention, had it since XMAS and I can see the sky pause and circle in the bottom left hand of my screen against bright backgrounds, and no, we don't pause for hours on end... .

It can be cleared up easily by switching to analogue aerial input without a lead connected, you get the white ants on screen, leave that on for a few hours and it will clear up any retained images.

So the answer is that they do, but can be remedied easily, which wasn't the case in the past.

Just reminds me that I need to check picture settings, it may set a little too bright and contrasty, hence the retention.