All these add-ons that come with load configs like PSS, LDS, PMDG do they actually reflect the load that you put on them? Just wondering if you give a plane a higher payload in the load config that the plane will actuall fly like a heavier airplane or is all this load config like "eye candy"?

It makes a big difference. Try it yourself. Take off empty, with fuel for a short "ferry" trip, ie. KLAX KSAN. Then try it again fully loaded and with fuel for a long trip and you will really feel yourself struggling to get off the runway. It's more pronounced in the larger planes. The RFP 747 can weigh over 750,000 lbs. That's like 375 tons. Yes, that eats up some runway. :-)billg