how to build on your own land without Gov linden returning yourstuff.

Excellent post, Imnotgoing, but I'm no sure I'm following you on this point. Every megaprim has the same poly count as it's regular prim counterpart. A (spherical) sculpty always has a max of 2048, a sphere always has a max of 528, etc. The poly count does not go up just because the prim gets bigger.

Or are you just talking about the fact that LOD will not be reduced as quickly, if at all, over distance on gigantic prims?

Yes. (^_^)

None, from what I've personally observed. I wanted to check here about possible issues I may have missed, hence the current discussion lol.

Hanging around in Sandbox Island frequently I've seen structures eating up almost half the sim area, some made entirely of normal prims and some with a lot of megaprims. The normal prim builds of the same size as a megaprim build are definitely worse for server lag and to render on the client end. I believe the reduced prim count outweighs whatever problems megaprims may introduce at this point. Moderate numbers of tortured megaprims don't seem to hurt anything either from some of the mainland builds I've come across. Larger amounts may be different but I haven't come across such an extreme yet.

Making dozens or hundreds of megaprims physical can get kind of laggy but then I can't imagine a reason to need so many set to physical other than griefing.

It seems to me perfectly easy to center a 256 x 256 prim in your own 65,536 region without encroaching on anyone else's land. But the OP here said he was using this to make his own sky. I can see how that might be nice if you were sitting in the middle of your own sim. But to your neighbors, how would this look like anything but a horribly mismatched invading Borg Ship?

I am guessing that the neighbors AR'ed, and even if the prim wasn't encroaching, it got removed over the technicality of "huge prims okay for now but will be removed if they cause problems..." etc., or however the Lindens have worded that warning.

I'm wondering whether the potential for severe visual blight is one of the considerations the Lindens make in huge-prim complaint cases? Don't get me wrong, I have mega prims all over the place, but I try to use them responsibly. I certainly hope that any neighbor can't just arbitrarily fill the sky or space with huge sim-sized prims, and our only recourse is to pray that they are encroaching, or blame them for the lag.

I suspect it was more that he'd done a custom sky than he'd used somebody's prim.

It looks like the OP does indeed own this entire region, except for the SLRR tracks that run straight through the middle of it. (edit: er.. maybe not straight thru the exact middle - I assume the OP owns 128/128, if he really wasn't encroaching..)

If you go out to where his land is, there's Protected land with a road that crosses the sim, hence he's just out of luck for a sim-sized prim, period. Someone else may have complained but I'm pretty sure it was due to it crossing the Linden road that got the megaprim removed.

If someone decided to create a flashing, seizure-inducing 256x256x256 lolcube that would get removed since it would present a myriad of potential issues. But unless it's a severe public nuisance, ugliness alone won't get something removed. That's life on the mainland.