On our trip to Tennesee , I had 16-1/2 lbs in each side case, and about 20 lbs in the top case, along with my wife and me (about 290 lbs suited up total.
Although I could feel the extra weight at stops, I had no handling problems. Had the rear shocks set to "high" and added a bit more preload up front, but that was it.
My wife says she was completely and "lavishly" comfortable on back with eh added backrest pad to the Yamaha top case.
As suggested, I would not load the bags with much more weight than this, and because of the aerodynamic issues with the top case and riding solo, one should add a bag between the rider and top case if no passenger is present.
Make sure to check your tire pressure now and then and remember that extra weight is back there...as the bikes performance will not really seem to change...
KM