I have emailed Samsung today and got this response!
With regards to your query about different panels in the F5000 model, I am sending this email to confirm that the same panels are used in each TV. Having been purchased from a legitimate company you are guaranteed that this Samsung product is manufactured using the correct parts.
Our engineers have not made us aware of any problems you have mentioned are contained within these AV forums. Therefore, we are in no position to go by this information.
If there is anything else we can help with, please let us know.
So according to Samsungs own techsupport all the f5000's will have the same panel!!