I agree. The UPP and the #16 are both great products (among my very favorite LSPs), but I wouldn't use them on the same car.
Topping the UPP wouldn't, IMO, add that much to the look but would decrease the slickness and prevent you from adding more UPP.
Try the
AIO/#16 combo on another vehicle and compare.
If you only wax when it needs it, and don't waste any by applying it too thick, two cans of #16 should last you for years. An application takes *very* little #16, as you oughta put it on very thin. And it lasts a long time.