Possibly the biggest concern is not the pack performance, but simply the weight of the pack. Some prefer a larger pack to help settle the car down, some a lighter pack for more nimbleness.

No need for great packs, since it is real easy to overpower a 2wd mod buggy with motor. Many (most?) of the top mod buggy drivers use lower C sport packs and/or turn the punch down on the ESC. And with proper care they aren't hard on packs.