I can’t really answer your question as it’s not a shot I’m specifically partial to, although I keep telling myself to try it out for a while. The problem is that what I do works just fine! If your shot will hit the spine in the chest area I'd think it should work just fine.
I'd guess that the story related in the other response was due to a shot that went somewhat too high. Spinal shock knocks the animals right down and often you unload the rifle and walk up and your trophy jumps up and runs off, with adrenalin in the driving seat. You may never find those. I've tracked a Springbuck on foot in the Kalahari for 5 hours. The animal was hit through the spinous processes in line with the shoulder with a 300 WM! Thankfully I caught up to him just before dark.
I strongly recommend you buy "The Perfect Shot" (by Kevin Robertson – “Doctari”) either the mini or full edition. It contains a lot of good pictures of animals, including the bone structure drawn in. The choice of caliber and bullets recommended may not agree with what we at LRH like to use (or my preferences) and I have seen opinions differ on some of his recommendations, but he is experienced and widely respected and certainly knows more than you or I probably ever will. The pictures are really useful. The few $ of the cost of the book compared to the total $ of the safari make it a worthwhile help to ensure your success. You can look it over on the plane.
In short I like the "Vital Triangle" shot where possible, but friends have had good results with the high shoulder shot from time to time. You need to know the anatomy as was pointed out by others (Blue wildebeest is the most risky, gemsbuck too, but less so). I've used the shoulder /spinal shot with some success, through the centre of the shoulder blade, but this is lower than what I've seen in long range videos of elk hunting. This was not on the larger species.
I'm not that sure about elk anatomy as you aren't about African animals, so it makes it harder for me to comment. Usually you can see the bones through the animal's skin here as the hair is short and the coat shiny in most cases. You will see a V on it's side created by the shoulder blade and the humerus, with the shoulder joint the point of the V. This helps if you want to take a shoulder / spinal shot. Most like to just slip the bullet into that V and results are good. Your PH may well have shots he likes or hates and I strongly suggest you discuss your preferred shots and his with him before the hunting starts.
Beware of side on neck shots on both Wildebesst and Gemsbuck as well as the spine does dip very low.
I’ve hunted those animals, some with various calibers, (not because I’m wealthy, but because I'm South African
), and mostly with a 300WM with 210 VLD’s which is my favourite for the larger species in plains hunting.
I’m not sure whose rifle you will use and what caliber and bullets you intend to take and that can be quite a relevant discussion too. Namibia has very varied topography and vegetation, so your hunting conditions are also not clear to me.
Best of luck. I’m sure you’ll love it.