Yeah, the Rock Racers are capable crawlers, but they are NOT a comp. crawler..cant speak for this one yet of course...
If you're asking does it have a 2-speed tranny? I dont think it does but Axial may surprise us?
What the dig does is allow you to engage another servo that will allow the rear wheels to lock in place but allows the front wheels to turn...kinda turns the front like a skid-steer bobcat... You will see what I mean toward the end of this video-
http://www.youtube.com/watch?v=fzM0g-qC_OE
I'm sure from the factory these machines will have good articulation but if you arent happy with what comes factory, make some changes and figure out your personal setup that suits what you're doing
As with anything else, one man's setup isnt always the golden ticket for everyone. Some guys like droop and some like it (lmao) "stiff". I dont care for the droop setup, but I'm running a scaler. When I was running a AX-10 I ran droop. Just all depends on your style and what you're doing with it. Good Luck!