There are some major issues associated with avatars crossing sim borders, as well as behavior across sim borders. This becomes especially apparent in 4-sim intersections, and where 4-sim structures are built over the intersections. 1. An example of a 4-sim Class 5 private island theatre. Please visit the SL Globe Theatre, at http://Slurl.com/secondlife/sLiterary/23/13/23 . The SL Globe Theatre is a 4-sim round theatre, with seating spread out circularly spanning 4 sims. The stage is on its own sim. 2. "ctrl alt shift 9" and view landlines and try crossing the sim borders. (Make sure you're not walking into a wall) Notice the oddity: a. Crossing sim borders on the pits – avatars appear to slow down and ruth (or partially ruth) b. Crossing sim borders in the galleries – above and also prims randomly turn phantom, even if "helper" prims are placed in both sims to facilitate collision detection. This may result in avatars getting randomly stuck inbetween prims. 3. Flying across sim borders: avatars often land at a huge and impossible z (even if they only planned for a long jump rather than any real flying) and are logged off.