Digital servos were originally developed to me more precise than an analog servo for large scale pattern planes where precision is a must. Digital does not make a servo stronger or faster, that's still a function of the drive motor and gearing. The actual difference between a digital and analog servo is the number of times it updates positioning input in a given amount of time. The digital does it about 100 times faster than does an analog. This keeps the servo from "wandering" off it's desired position between updates.

As for your radio being digital, all that means is adjustments are made via electronic pushbuttons with the results displayed on a screen rather than using dash pots with a graduated scale on the face of the transmitter. You are still sending the same signal as any conventional surface transmitter so you have nothing to gain by using digital servos with your "digital" transmitter.

That said, the only thing using digitals in an off road buggy does is force to be extra careful with your EPA's. If you set a digital servo EPA just a tiny bit past the physical limit of the linkage you have it attached to, you risk burning it out due to the extremely high refresh rate. Digitals are also big power hogs so you will also need to use a larger capacity receiver pack to compensate. For my money the Airtronics 94357 for throttle and 94358 for steering is the ideal combination for an 8th competition buggy. They are plenty fast and strong to do the job and they are like an anvil, almost indestructible.