I love the addition of collisions to the models, but there is a really difficult issue.
Importing anything bigger than about 2 meters causes the object to rez in the same vicinity as the avatar, causing the avatar to get physically locked into the model and unable to move up, down or along to escape.
All the while the scene and avatar are shaking violently.
Importing a building is a major hassle.
The workaround is to either TP away and back again or to turn off the Avatar collisions from the menu.
I’m sure you have a solution in mind but I can suggest the model rezzes at a distance away 1/2 the size of the object, so it is not in the same space as the avatar.