For what it's worth to the perusers of this thread...
I am the  admin over there on SI3D and am currently re-vamping alot of the content  to work out of the box as a more competant modeller now I can offer  more custom dependancies which I am able to distribute and have gained  the relevant freeware distribution permissions/licenses from the authors  of any 3rd party content we use. 
Simply put, from now on when  we release anything that isnt a route, you should have all the  dependancies you need included. Out testing is more rigorous now which  should hopefully sort that out too. 
The only thing that wont change just yet is the hosting provider, but I am looking into possible alternatives in the future. 
Hope this helps you. 
I've  tried to keep SI3D out of this forum simply because I know how some of  the more serious railway enthusiasts here, myself included enjoy the  absence of the younger genres and the fanbsae that comes with it. I have  always thought that to be a nice seperation but obviously will help  anywhere i can.