I have had the 600 watt and the Rx for several years now and they work great.  I recently bought the 1200 watt and it is the perfect amount of power to blend my smoothies.  I have read that other people have had issues with leaking and it not blending thoroughly, this is usually due to not tightening/securing the extractor blade enough, and make sure to cut up your vegetables and fruits before hand.  I blend my vegetables (spinach, carrots, broccoli, cucumber, etc.), almond milk, protein powder, oatmeal, and walnuts first, after that is blended completely then I add frozen blueberries and strawberries and blend again, comes out perfect every time.  Make sure to order and replace your extractor blade every six months, it does wear out.