I have a couple of questions....

[lincpimp]

I would say 2 2s packs. More useful and easier to package. Plus if you get a smaller/different vehicle and want to run 2s you already have the pack. Unless you can get a deal on a 4s pack, sometimes that happens. The 4000 10c truerc packs will not be enough, you need a pack that can handle about 80 amps continuous. That is why i recommended the trakpower packs. The truerc 8000 packs are much bigger/heavier and cost the same. You may get better runtime off the 8000 packs, but the cells are not as good and heavier. A lighter vehicle is always better as it works the motor/esc/batteries less. I do not have enough experience with my maxamps 5000 2s packs yet, so far I have only run them in my 10th scale lighting conversion truggy, so not as much load/weight as you have. I know that the trackpowers are good, seen plenty of data to prove that. Just remember that you have to have the v balancer to go with them.