I see there are some settings for Roche Limits, but I'm not sure what realistic settings would be.
Hmm. That was not really supposed to be there in this version, since there are issues and the visuals are not tuned for this at all. Well, now that it is included, 1 is "realistic" and 0 is off.
What this essentially does is calculate the "Roche limit" for a body and its strongest attractor, and break the body when it is closer than that limit. Setting a value of two would make it break up twice as far away.
..but... the Roche limit is really meant as the closest distance from a planet, where a moon may form from coalescing particles. It can to some extent be taken as the distance where an already formed moon would break up (over time), due to differential gravity on near and far side, but it is not a magical distance where moons just blow up.... which is what you will see now.
To try it (which you shouldn't, since it is not supposed to be there for you to see!
) you can set "rocheSensitivity" to 1 and create the earth moon collision. The moon will fly in and then "pop" break up and impact as a mass of fragments. Then you can shoot moons (4) or other bodies near earth and see the same breakup. Grazing collisions become a bit more interesting this way. The hope is to solve many of the collision issues by breaking bodies apart during collisions as well.