I can comment some on the East Cape vs. Limpopo as I've hunted both twice. I would say Limpopo is generally more flat to gently rolling. With some exceptions, we did climb some rocks and as you get North Around Louis Trichardt it gets mountainous. In Limpopo, you are mostly limited to hunting. In the east Cape, if desired, there are lots of other things to do, more parks and touristy things, like Addo, Shamwari, Schotia... And you have the Coastal areas. The East Cape is much more varied. My observation is that in Limpopo you will mostly be hunting fenced properties, although I took my Klipspringer on mountaintop in Limpopo that was cattle fenced, but certainly nothing to keep klippies in. I always though of Limpopo as big.. But actually hunted much bigger areas in East Cape. The East Cape kudu are typically smaller, tend to be very beautifully colored though. The cape bushbuck is more black with more pronounced spots compared to the more simple brown Limpopo variety.
In general kudu should be cheaper in EC, bigger and more expensive in Limpopo. IMO EC is thicker and thornier, I thought most of Limpopo is more open, but in March both will be green. In the EC you will have more opportunities to get up hills/mountains (very small mountains) to glass down into things and across to opposite slopes. I love hunting Black wildebeest, and the EC is the place to do that. Limpopo for blue ones. Red hartebeest is a great trophy you can get in either place, impala and zebra should be in both. Sprinbuck in the Karroo is loads of fun! There are springbuck in Limpopo, but not like the karroo.. Or the best are in the Kalahari. Another great trophy in the Karroo (again, even better in the Kalahari) is Gemsbok.
Both are great hunting, if a big kudu is a high priority, hands down Limpopo. More varied ground and if you like hils and mountains, I would say the EC. You will see lots of critters in both. I really liked the Karroo the two times I was there... My second visit to the Karroo I had the arrival late afternoon, two days, and departure at noon... shot 9 critters and passed on several... And missed a klippie and Vaaly. But we hunted hard and all day with packed lunches, and had two tracker/skinners