The bryce .obp will have all the texture information stored in it - that could be one reason its bloated up.

Another possible reason (which I'm not sure if its right or not) could be due to the type of mesh the obj is - maybe bryce has tripled a lot of your polygons, hence maybe doubling your poly count when it went from .obj to .obp. Couldn't say for sure though on that one, though I've often noticed that bryce thinks imported models have a lot more polygons than Lightwave (the source of my models)....sometimes by as much as a factor of 2.

Dreams are just nightmares on prozac...
Digital WasteLanD