I base it on a multiple reviews concerning the two and owning a Ballistics the following points are what I have found. I will say however, that the Shorai batteries in reviews I have read put out "slightly" higher voltage, like .1-.2, however both are far better than lead-acid batteries.
First and the biggest strike is against the Shorai terminals that were terrible and flimsy, they broke, and bent, and did all kinds of nasty things. Shorai did however fix this with a revised terminal design, so props to them.
Second, the internals of the Shorai are essentially the same thing as the Ballistic, however, it is a significantly larger and heavier package, raising the question of why are Shorais so big? Neither has an over discharge curcuit so it's clearly not that.
Third, and most important to the life span of the battery, as of last time I looked, Shorai does not have a balancing terminal on their batteries. Without this you cannot refresh the battery to new and extend it's life and accurate power delivery. Ballistic batteries have this terminal.
Either way, I think both would suite well, however the Ballistics 8 cell is significantly smaller and lighter than the Shorai, while providing the same function at similar price point with the potential for longer life.