A big noise of opinion from here is for you to just turn the factory integral speakers down to the off position. That necessitates a modest amplifier & a couple of speakers to start with. Sorry that means more money, but pleasure from the sound improvement is a matter of magnitudes. That will be some real sound projection that leaves the in set cheap tinny in the dust where they belong.

I have a secondary Panasonic LCD. Mostly watch DVDs on it. It's refresh rate must be around 16ms as it's 4 years old. Motion lag/blur just hasn't been noticable or annoying at all. To see how refresh has importance or not to you, spend some critical viewing time at a showroom when they aren't busy.