Which 4wd ?

[Robocop]

Hi
Need a bit if advice at present i have a cougar sv i have just come back to electric off road from doing 10th on road i was thinking about doing 10th on road but i did really enjoy the 10th off road that i did.Where i live there is not a lot of 4wd but if i did the nationals i would want to do both days.
So what i would like to know which 4wd a durango or a cat pros and cons, what is the main difference between the 410r and the other one,how much do you have to upgrade them to put more reliabilty on them,as on the cat they are fitting steel gears etc.
Thanks