Tell me More About Simple Actors in 3.1

For those of you using 3.1 tell me some cool things you can do with simple actors ... expand my mind.

Simple actors don't have any special features, and they have less features than normal actors.  The only benefit is performance.

So what are they good for?  Things like particle effects or not?

They're intended for decoration, but you can use them for particles too as long as you control the particles from another behavior and don't need them to collide.

Would they be good as barriers against which other actors that are moved by the player will collide to?

We've been having difficulty creating static actors to function as barriers. Always the other actors that move (using a variation of the  Movement behavior without cameras) they would go through this intended barriers (even with simple Physics, can't move, stone material and on the same group as the moving actors). Any suggestions?

No, simple actors have no collision at all.

Thanks for the info Rob.