Could you describe the system they use?
ehh, I don't really get what you mean... is it how characters collide into each other?
Anyway, in Tremulous, I have never seen at any time anyone being stuck in each other ... Nor did I see anyone stuck in a wall.
For the Death Realm, I believe it could be disabled. Anyway, it would still fit IC, with the "souls".
For the spawn point problem, in Tremulous, they have a waiting list for the spawns, so if 10 people die at the same time, all 10 won't respawn at the same time, they will respawn one after each other (bad luck for the 10th ...), so I guess this could be implemented in PS, although I often see people just staying on the spawn spot, not knowing what to do, or just being lazy.
Another thing with spawns (not only in DR, but also when a player spawns by joining PlaneShift), I guess it would be possible for them to fit into each other, because none of them moved (therefore, no collision), and as soon as one of the player moves, the collision system would bump that player out. I have seen that in other games, so I believe it should be possible.
About the problem of people staying in one place just to annoy ... I guess that it would be possible to make a system which disable the collision system with that person after X amount of time. Also, I like the idea of pushing, however I do not know how this might be implemented.
Another thing we would be possible to prevent characters from staying in one place, is to disable the collision system in areas very likely to be blocked (doors, stairs, etc.)
maybe it can be used for all the creatures, Like you can't walk through a Ulber and so
Yes, that would be really great way of implementing it, it would also avoid that cheat of walking through the creature and making damage without receiving any ...
Another "positive" thing about this would be that it would prevent 200 crafters from occupying just one single square meter (like you see near Harnquist ...). It would be much more realistic, however, I guess it will annoy the crafters ...