Shorty LiPo packs- what's the downside?

[Mark Westerfield]

The lighter weight of the shorty battery will have less weight on the tires creating a smaller contact patch for less traction, also there is less overall weight transfer (but faster) during braking/acceleration/turning. But pretty much everything can be compensated with tuning.

Generally, the lighter battery increases the power-to-weight ratio, which is usually better overall.