I was just thinking that it may be what soft you use, ulco. When I did it with my TG maze world, I added vines, then exported the terrain which had the vines in order to add more. That is when I saw that the vines I already added where exported as terrain.
I saw that in IvyGen, perhaps some programs read the exported obj differently. As this is a known issue with obj.
By the way, I found that having the vines in exported Terrain, really helped with knowing where to add more and not, so perhaps that is the most practical thing one can do with this.
I also was thinking that, exporting very small pops (say no more than a few square feet of terrain) could be a great way to make super complex vector brushes for Mudbox. I had previously argued that vector out would allow mud to be the sculpt tool for TG. But with the idea we are playing with now, This could be really powerful for mud (and maybe Z?). In theory anyway (and if it is possible to out as vector rather than obj).
Last thing, though I did not save any screen grabs from the ivy scene, I remember very clearly that the ivy exported from TG as terrain was VERY detailed and looked quite good (viewed in IvyGen). My obj files were I recall, running about a gig+ for that and that was way more then a few square feet of terrain, more like many meters.