lighter is nearly aways better.heavier planes must fly faster & at higher AOA inorder to develope same lift & will stall at higher speeds.acceleration is slower, landing speed is increased as is fuel consumption.full size planes handle noticably different when fully loaded than when empty. It is a myth that heavier planes "handle " wind better.that is a function of many factors including design. true, they may not get pushed around as much by gusts, BUT, lighter planes recover faster from any disturbances caused by wind etc.in fact if you suddenly encounter cross wind or tail wind (like downwind turns), the heavier weight will work against you. in placing aerobatic manuevers it is posible to be somewhat too light if precision is required. heavier only absorbs landing stress if the weight goes into reinforcing the gear. lighter planes land slower so the overall mean stress level is the same.