The 46FX is a good engine, but im not a big fan of the remote needle valve. I have had a few problems with air leaks in the past with one, and the fuel line nipple on the RNV is in a odd place making it hard to get to sometimes. I would definetly go with a Ball Bearing .46, there are a few other options out there such as GMS and the Thunder Tiger Pro series, I wouldnt get an LA engine from OS, they have nylon backplates and I have heard of tendencies of them breaking under certain circumstances.