Top speeds posted by most manufacturers are optimistic at best. Durability is a better goal. Top speed ultimately has to do with the surface you're running on, gearing and temperatures.
I would avoid Redcat as it has very little parts support or aftermarket parts. I would check the Losi 8ight buggy:
http://www.amainhobbies.com/rc-cars-trucks/team-losi-racing-8ight-3.0-1-8-4wd-competition-buggy-kit-tlr04000/p251040
This has plenty of support and is reliable and has plenty of...