I don't think it matters.
Kudu are in fact easy to kill. Wildebeeste and Gemsbok (oryx) have a reputation of being hard to kill but this is probably because their organs sit low in the chest. Hit a Wildebeeste in the center of the chest and you've passed above the spine (see "The Perfect Shot" by Kevin Robertson). It might make a difference on Eland.
I use 180 grain Partitions for all game in my .300 Weatherby simply because I don't have to think about it then. I have only recovered one bullet, an angling who at a Wildebeeste. All kills have been one shot kills.
