Robot must carry ~15LB between two waypoints several kilometers apart without GPS. Terrain is generic grass/rocks/dirt/sand whatever is in the way. The lighter the robot is the better.
I don't consider brushed motors an option. For example, this 3000W motor from NPC:
http://www.npcrobotics.com/products/...at=20&mode=gfx
weighs 15 pounds. A brushless motor of the same power would weigh around a pound.
We still don't know exactly what the robot will look like and not much planning has been done yet, I'm just looking at some options. I'd like to avoid ackerman steering because some of the manoeuvres will need to be precise but it depends on what the software guys want. Crab drive/meccanum wheels and skid steering are also all on the table.
Given how light brushless motors can be it is my opinion that it is easier and lighter to have a separate motor for each powered wheel since there will be some form of suspension.
Hoping for a weight of ~40KG and a max speed of 4m/s.