I don't agree that the only differences between LP and LI are the pace.
I think that in LI, the offensive flow of the team is very strongly determined by the PG, especially his passing and handling. In LP, there's more involvement of each of the players, and so I think it works a bit better if your passing and handling is good team wide. I also think there is a slightly higher number of shots taken by the big men in LI compared to LP.
So, if you are stuck with an atrocious inside shot guard, but you are set on playing an inside tactic, I'd likely go LI, as long as that guy has decent passing.