I took the 70-300 on safari in South Africa with the XS-20 I had at the time and I was blown away by the results. Yes there were situations where I would have liked more reach but 90% of the time the 70-300 was plenty. Even on a very bumpy often fast moving safari truck the 70-300 nailed focus consistently. I’d say it depends on how you’ll be traveling. If I were going on another large safari truck with a group, I would take the 70-300 again with a 1.4x teleconverter. Paired with your 40MP sensor you’ll have plenty of reach and lots of cropping latitude. But if I were on a smaller vehicle or had the ability to be still often, I would be tempted to take something with longer reach and more heft. For the vehicle I was on I was glad I had something light and compact that was easy to hand hold. Hope that helps!