Parts are not an issue for the clod buster. Not only has Tamiya made every spare continuously since 1987, the aftermarket support alone could keep the clod alive without tamiya.
The thing brushless would be hard on besides the budget would be the truck overall. As stated above high speed crashes are harsh enough with a well built race clod, and a stock clod would be breaking plastic everywhere.
The super rooster may have a 15turn motor limit on 12 cells or something but I know for a fact they can run down to 9 turns on 8 cells with no problems as I have seen this first hand. 17 turn motors should be no issue.
Do not get a super duty, they are garbage. I cannot tell you how many racers have burned these up under conditions that novak says they should be fine under.
One more thing, I'd reccomend a single battery pack. It will still be plenty fast with 17's and a single pack and the reduced weight will really help durability and capability.