I'm probably not the person to answer this but I will give it a try. First off the TRD PRO is going to be harder to find and depending on the area and dealer you may not get much of a "deal" on one. Second, the TRD PRO has a beefier suspension, different front and rear valances and does not have KDSS as an option. Third, you get narrower TRD PRO wheels (which look cool, imo).
Slightly embarrassing to admit but I went with the Off Road premium for the looks. I even told the salesman that I doubt this thing will ever go off road. After browsing here and watching videos of what these machines are capable of, I have changed my tone. I enjoyed seeing mud dripping off of it more than I enjoyed seeing it after a complete wax and polish.