Colin
Have a look at the Extreme Flight range from West London Models, they have a 48" Vanquish which I have flown a few times and flies very well, as well as anything in this size. It will have excellent performance on 4 cells. They also do several other models in the same size range Edge, Laser, MXS, although designed for 3d they also fly precision style very well..
They are a bit more expensive than some others, but well worth the extra cash as they fly very well, are light and very strong. You will also see second hand ones come up occasionally. Being wooden they will fly better than a foamie, depends what you want.