I will try to answer your questions..

I don't know what you mean by power.. Speed, Torque? both?
Well the T-maxx has higher avg speed and E-maxx has lower speed than the T-maxx. The E-Maxx probably has more torque due to the fact that electric motors have more torque and reach higher torque faster than nitros.

By the way the E-maxx and T-maxx aren't really rock climbers but more of an offroad, dirt road jumping, running, and bashing. I guess they could be converted into one but thats another topic.

Electrics usually cost more initially and nitro more in the long run. Nitros tend to have longer run times depending on the engine size/fuel consumption and tank size.

The basic difference is their powerplant and power source. I won't go into every part that makes it different or such.

Regardless people like what they like either nitro or electric, its up to you and your preference. As long as you have fun with it its all good.

Also think of it this way.. You can run a nitro long as you want as long as you have enough fuel. It can be costly in the long run but in the short run, cheaper than electric.

Electric in the short run costs more but in the long run cheaper.
You might have to buy 3-5 sets of batteries to help you run longer. You can cycle in and out batteries and that will help you last a long day. Batteries can last you years if you take care of them. I would recommend either 3000mah or 3300mah ratings for batteries for longer run times.

Personally I like batteries and nitro. They both have cons and pros. It's up to you what you prefer to do.