I have been doing some more reading on the FX's. Maybe they aren't perfect for my set up. My room is 20'x20'. The seating position will be about 12' from the screen which will put the rear speakers about 5-6' behind the listening position. I am reading that the FX's should be placed 1-2' behind the listening position. I can not use side speakers due to the room set up.
That's a preferred position. A guy has got to do what a guy has to do.
IMO, the FX's will work great for you, they create a more indepth sound field. I use them for side surrounds and eventually heights.
If you want to use 45B's for heights, I say go for it. A bigger speaker will give you bigger sound, I've proved that over and over in my own set up.