Canon EF 70-300mm f4-5.6L IS USM or Canon EF 70-200mm f2.8L USM?? 100mm diff...

I am going to south africa for 3 months for work and intend to do wildlife photography in the national parks nearby.

I want to invest in a L series telephoto lens, but I am not sure which one to get..

Canon EF 70-300mm f4-5.6L IS USM $1434

or

Canon EF 70-200mm f2.8L USM $1,374.99

there is an 100mm diff between them.. how much does that actually matter?

i know that the 200mm is alot faster than the 300.. i have a tripod but i think it will be handheld if I am in a rush.. so the 200mm does not have IS and the 300mm have IS.. will they kinda equate.. since IS can compensate 3 to 4 stops..

which one should I get??

I have the canon t2i.