I´d personally go for a 511, this car is by far the best i have ever driven in the last years. I was in the same situation wehn someone wanted my DB01R that had some Hop Ups, i still made a bit loss but having the 511 now makes me forget that
The DB01 is a good Chassis but if you would have the chance to race it side by side with the 511 you would know what i am talking about.