The e-revo w/ 8xl will get 90% of your use... you decide what to do from there. If you have lipo's with an 8XL you'll have more torque and top end than you need, so you wont need two trucks you need good throttle control :P or swap out a spur to control speed maybe..
Here are a couple video's to watch.. the emaxx is with a 7xl the revo is 8xl (4s 2s2p 6k lipo's and MM controller)