Monitor Audio Silver RS8 vs GS20's

Hello all, I have the RS8's which I like a lot, and am looking at some GS20's.  Specs look very similar and the RS8's have one more bass driver which seems like a plus.  Aside from going from "silver to gold" not sure what more, if anything, I would get from the GS20's.  Would be playing mostly classic and progressive rock with some power-pop, metal and punk mixed in via either a Sansui AU-D7 or Peachtree Nova 150.  Room size is aprox 25'x15'.  If you have some insight, I would love to hear it. 

Thanks!!  John