I was in Tanzania last year, and even with an all-inclusive limitation of 19lbs of gear per person, I still chose to bring along 11lbs of Canon gear (body, wide-angle, super-telephoto, tele-converter, double battery grip, extra batteries, chargers, power adapters, a Nexus 7, USB OTG adapter with card reader and SSD). You'll get some fantastic sharp daytime landscape shots with a 6P, but as soon as you need optical zoom flexibility, low-light performance (trust me, this is big for the early-morning and sunset safaris) or really want to capture the unique colors, you'll regret not having a proper DSLR sensor and lens.
A DSLR can run laps around any cell phone in terms of burst performance (capture interval and capture count) with proper cards, and if you're looking at a DSLR for such a trip, you're also looking at shooting in RAW, no doubt. The advanced stabilization modes (see
this review) of high-end telephoto lenses are unrivaled by even "kit" lenses, let alone a smartphone -- services like BorrowLenses make it affordable to rent high-end gear for once-in-a-lifetime trips. I rented the Canon 200-400 F4L, but the 100-400 with or without an extender, or any other similar setup, would still be in a completely separate class than any phone.
That said... if you're going to be spending a few days with friends or family in less remote locations, you won't be looking to have that DSLR just out and around for photography, for reasons of security, damage, convenience, and so forth. The 6P will be perfect in that case, and if you're on a carrier which has a 2G/3G arrangement for the country you will be in, you'll appreciate having it that much more when moving through any towns that have service. Bring a USB OTG adapter for your cards, and you can cherry-pick photos to show off on the awesome display while in-country, or even back up to the cloud if circumstances allow; one of our overnight stops while traveling had a satellite linkup with WiFi, so I backed up a couple dozen photos just to be safe. Couldn't have done that without a phone, USB OTG, and card reader, all of which are small in weight and size. Plus its battery life while on airplane mode should be excellent.