Hi,
sorry can't comment on the 300 never driven one but have driven a 450h a few times,
it's a fantastic car very quick with loads of mid range power.
is it a lexus dealer? if so i would ask for a day test driving each and see which one you prefer.
the dimmer/brightness control on mine is to the right hand side of the steering wheel,
but if you turn it past the click then it's in day mode and the screen is bright all the time.
hope this helps
sorry can't help with your claim but hope your successful.
just wanted to say i'm gutted for you thats one nasty pothole
also do you know the name of the road if so think you should name it to give fellow members a chance of avoiding it.