using the same chart and data your 800 gr arrow beside arriving .2 seconds slower at 60 yards will also have a drop of 154" while the 450 gr arrow will only drop 91". That's over a 5 foot difference. There difference in KE is only 4 ftlbs at this distance. You will have more penetration with your heavy arrow which is definately a plus when shooting at large dangerous game but not really necessary for deer elk or black bear. In sparse cover I would have no problem with shooting a heavy arrow. But hunting in heavy cover with small shooting windows or longer distances like out west for antelope I'd much prefer the lighter faster arrow. Both have their place and sometimes a compromise needs to be taken to give the individual his or her greatest chance at success.
Good luck on your safari and stay safe.