Should I exchange the SX50 for something better in low light and action mode??????

See this is my problem. I am really not use to anything and want to get the best for what I want to do with it at this point. Does that make sense? I like the camera...its a bit daunting to me with the settings and such but any of them would be at this point since I am a total novice. Is a 2.8 lens a lot larger then this one on the sx50? I am trying to understand it all but having a hard time...its a lot to absorb. Thanks!