I am looking to replace 10 500W halogen outdoor fixtures(rectangular shape approx5"x7" with 1/2NPT threaded base), any suggestions on an individual fixture that would be comparable in lumens to that. Owner does not want the halogen type because of extremely short bulb life,any thoughts on a type of fixture(HPS, MH,) that would give me comparable light. The physical size is an issue, and the 1/2NPT mounting base is also important because it would make remounting the new fixtures very much more cost effective. Thanks.