The Traxxas rally is technically 1/8 scale (like most SCTs), and SCTs (or SCT based rally cars) are noticeably better off-road. After my attempts at "rallying" touring cars, I just use them on dusty pavement.
The big caveat with the Traxxas Rally? It uses a clipless body mount system, so...
A 4x4 SCT will certainly be more capable off-road than a 1:10 touring car, but they tend to be more expensive too. That might be better later down the line.
Universals axles, metal driveshaft, probably a few others that I don't know of.
For brushless you'll likely want the metal driveshaft, a bigger pinion gear, aluminum motor mount (if the car doesn't come with one), maybe a cheap fan/heatsink if it runs hot (anything for a 540 motor works...
I'm not sure how long, but it's worth the wait if you end up saving $100. Hop ups are significantly cheaper there too if you go that route. The XV01 has bearings, shocks, and will offer a more involved build than a TT02.
TT02s are delicate as far as "rally" goes, mine would strip the steering...
I currently own an XV01, and have owned several "pimped out" TT02s courtesy of the used market. I've had better luck getting a $15 cat toy to track straight (let alone a Grasshopper, WPL, Nikko, etc). I can't tell you how many holes I've stripped or rounded out on my TT02s too, despite being...