If you are going to use the plane for either just 3D or just pattern, go with the .46 as it is lighter.

But If you are going to use it as a dual purpose plane, go with the .53, this way you will be able to run a higher pitched prop for pattern, but still have enough grunt for some 3D when you feel like it.

If you put a 10.5 x 6 or similar higher speed prop on the .46, it won't develop anywhere near enough static thrust for 3D, not on a 5lb plane anyway.

It is really quite amazing what difference propellor sizes make to static thrust readings.

If you use the OS, it might be worth changing the muffler from the stock one, it is only a silencer, and is not tuned. (so I am told).
Put a GMS / Tower muffler on it and it will really come alive.
ie+ 1000 rpms or so, it's louder, but worth it.