Questions about the weather engine

Hello,before buying AS2012 I have some questions about the weather engine of AS2012. For me, the mainly reason to buy AS2012 is the weather engine, i don't need the textures because I want to stay with other textures I use since a long time. Is anyone able to say something about the performance influence when using AS2012's weather engine in comparison to the freeware weather engine FSrealWX ? (I use NOAA weather) How heavy is the loose of performance when using the direct weather control? Can somebody post a screenshot of the AS2012 fog? (Because of the new technique of generating fog with clouds? ) thanks for your help ;)