RE: GSP planes, made by......
Sorry to say this but CMPro planes are not the same as WM stuff ... look carefully they are very different. CMPro line of planes are also very different from WM ones. WM planes are a lot lighter than CMPro planes too.
As for engine choice ... get a nice OS160FX for the Extra, you will not regret, also the MVVS 160 will be more than sufficient for aerobatic flying, not 3D of course. You wuill have very good verticals.