Right that makes sense regarding the fish eye and yes that 80 - 200 gets heavier each year .. I have dragged it and the 35 - 70 2.8 all over Hawaii for three trips.
Since you have the D300 do you shoot jpg or raw at sporting events like a football game. I almost always shoot RAW but it seems that even 12 bit RAW slows things down a bit when shooting multi frames per second.
I don't use the extra battery pack just standard batteries.
AKA : Sal Ficarrotta in some parts of the universe.