Sorry getting this late into the discussion with the polys :)
I have imported many of the new models (mainly the adult trees) and saved them as .vob, no problems with the polygon count. (I've done so many times before, both with XFrog and Onyxtree hi-poly models).
I prefer the 3ds export, and don't weld the model right away, maybe some tweaking is needed. E.g. the tree species with the roots are awkward for use with ecosystems (they need to be "sunk" into the ground), so I "boolean away" most of the root object (it can also be deleted).
Also, I work a lot on the textures.