At a british webshop i can get a g85 12-60 kit and 100-300 ii with a combined cashback of 200£ for a total of ca. 1000£
Seccondhand locally I can get an em1 with battery grip in really nice condition and a 50-200mm Swd +1.4TC for ca 800£
Which is the better option for my upcoming trip to SA.
My current kit is em10 Mark 1 with oly 17mm 1.8 oly 45mm 1.8 pana 12-32 and 35-100 kit lenses.
As much as I've been an Olympus shooter since 2002, I suspect the best bang for your buck is the G85 with the 12-60mm kit lens and 100-300mm mark II lens (make sure it is mark II). Particularly, since the E-m1 is used, and you might not know how used it is.
I assume in your E-m1 kit, there is a MMF-3 adapter for the lens. If not, you will need to budget for one. If you need weather sealing, you want the MMF-3 adapter, and not the earlier Olympus/Panasonic/clone adapters.
I do shoot regularly with the E-m1 mark I and 50-200mm + 1.4TC (though note, I have the first generation 50-200mm, not the 50-200mm SWD). I recently got a G85 to go with my E-M5 mark I and E-M1 mark I. I have not used the 100-300mm mark II lens (or the mark I version). I have briefly tried the Olympus 75-300mm in the store. I have not been to Africa, so I can't comment on the conditions there.
The main reason I got the G85 in this upgrade cycle rather than the E-M1 mark II is that it has an OLED viewfinder. This means I can clearly see the VF when I'm wearing polarized sunglasses. My E-m1 mark I and E-m5 mark I both have areas that you can't see when shooting in landscape orientation (i.e. normal horizontal shooting). The cameras VF is viewable when shooting in portrait orientation (i.e. vertical shooting). I have tested the E-m1 mark II in the store, and it had the same behavior. Note, I am generally ok to frame the shot even with parts of of the VF not being visible.
So assuming, you are going to be shooting a lot in very bright conditions, the G85 wins out. In terms of Olympus cameras, the Olympus E-m10 mark II and Pen-F also have OLED viewfinders (I don't what the E-m10 mark I uses, but I assume it is the same VF that the E-m5 mark I used).
In addition, using those two Panasonic lenses (12-60mm and 100-300mm mark II), those lenses have stabilization built-in to the lens as well as the sensor based stabilization that the G85 has (the E-m1 only has sensor based stablization). I would think that since the G85 can work with both stabilization systems that it would give better results. The typical consensus appears to be that sensor shift stablization works better for more wide angle subjects, while lens based stabilization works better at the telephoto end of things. I don't have a lens with stabilization that I shoot with (I do have the 12-60mm kit lens, but I haven't used it), so I can't say whether that is true from personal knowledge.
In theory, the DFD continuous focusing on the G85 helps with the two Panasonic lenses. Since I don't use continuous focusing and I don't shoot with a lens that works with the G85 DFD, I can't say whether it helps from personal experience. But others like it, so read their reviews.
One thing that the E-m1 wins out is you would get the HLD-7 grip, which would allow you to shoot twice as long without changing batteries, since you have 2 batteries. In addition, if you are mounting the camera on a monopod/tripod, you can change the bottom battery while the camera is mounted without having to remove it from the monopod or tripod. You can get a battery grip for the G85, but it is relatively expensive.
A lot of people like shooting with the grip, particularly with the heavier lenses like the 50-200mm. For normal shooting, I tend to not put my HLD-7 on the E-m1 mark I, but if I'm going to be shooting all day, I do put it on. The grip has extra buttons to help if you are shooting in portrait orientation mode. I generally turn these off, because I find I tend to turn the two dials by accident. I don't have the grip for the G85.
Now, the lenses in question will be shooting in the f/4-5.6, which are great for daylight shooting. However, the cameras will struggle if you are shooting at dusk or dawn in lower light. You would have the 17mm and 45mm for low light shooting (but not at a distance). The 50-200mm SWD is one stop faster if you take off the TC.
As I mentioned, I have the original version of the 50-200mm, which has a sensible lens hood that fits nicely on the camera, and packs nicely. The lens hood on the 50-200mm SWD lens is much bigger, and it means it is harder to pack your gear in a backpack or suitcase where you are carrying a lot of gear.
Note, the 50-200mm SWD is 995 g (2.2 lb/35.1 oz), the EC-14 is 170 g (6 oz), and the MMF-3 is 42g (1.6 oz) or 1,211g total (2.7 lb/42.7 oz). The 100-300mm mark II is 520g (1.2lb/18.3 oz). At the end of the day that 700g/1.5lb difference might be a factor if you are shooting freehand.
When I'm shooting subjects with little contrast (such as whale watching out in the ocean), I find the E-m1 mark I/50-200mm/EC-14 struggles getting focus. When I last went whale watching, I found myself switching to the 14-150mm mark II lens, and I was happier. Now, if there is plenty of contrast, it focuses fine. I got many great shots with that combo of surfers when I was on vacation in Hawaii.
