I think the 80-200 f2.8 is a very good choice as you will find faster focus speeds and being f2.8 should be quite a bit more accurate as well. If you are looking to save some money then the Sigma 70-200mm f2.8 is a good option, this is the lens I use and is only really let down at 200mm f2.8 where it is quite soft but stopping down (as you would for most motorsport) it gives great results.
When using the Nikon (if you go that route) then you will want to use a monopod as it is not a light beast.
More than likely go with Nikon. If my previous Sigma APO is anything to go by (as much as the shots were pretty good!), it'll be quite slow compared to the Nikon.
Not handled one yet but I'll see how I fair with good old human energy, firstlol.