Hey Tim,
So I was also in a similar situation and here are my findings
First I purchased a 41" 4K (non Smart) TV for $299 pre-order. This one did not have an LG panel. Watching TV in non-HD channels was unbearable, awful. So I returned it.
I exchanged it for a 43" Full HD Smart TV with an LG panel. I think it was $450 delivered. The results was MUCH better. I could not be happier with the TV. Its great and works well with the amp that I have two way HDMI Arc. However, the "Smart TV" bit of the TV is SO SLOW that its almost non-usable, almost. But in my case, I have an external media centre so that did not worry me no do I use this feature.
So basically, if you are going to match normal TV, don't get a cheap 4K TV as its only optimised for HD and 4K pictures. The cheap Full HD TV has both great normal and HD viewing.
Hope this helps.