I can export with Bryce 6.1 with or without textures. The problem is as Wyrmshadow pointed out. Bryce does not have good quality on the exported meshes. You need to import them in to another program to weld the pieces back together. The underlaying problem is that Bryce does not actually collapse the booleans. The collapse gadet could better be described as a "hide" gadget. You can test this by making a complex bool in Bryce 6.1, save it to your library (obp). Move this OBP over to Bryce 5.5 and it opens just fine. But, it unhides the stuff again.
Also, with very complex exports bryce adds stray polygons. And either deletes or reverses the normals (reverses the facing) of a few others. This does not happen on basic models, only when you get a little out there. I was modeling a robot in pieces and exporting them out bit by bit and importing them back in to save memory. Because since Collapse does not collapse, it takes just as much memory as before. And Bryce as a few issues with overly complex scenes... for example, it not open any file no matter what once it gets to 2gb. Not an issue in making units, but you can hit that limit pretty quick when going for photo-realistic renders of complex scenes.
On the textures, I suggest you never export with textures, but not due to any crashing But because the default mapping is not very good. Instead export it as a OBJ, import this OBJ in to UVMapper and make a map_template for the object. Save out this modified OBJ and the template and apply your new texture to the object this way. Far more precise. One of the many reasons why Wyrmshadows units look so good is that he tends to use UVMapped textures. These fit better and enhance the look of the unit without taking "too much" memory. In Bryce you use Parametric to apply UVmapped textures.
Better still is to re-create the bryce models in another modeler. It will not take "that" long. Since you know boolean modeling and are good at it, I suggest Truespace (exspecially the older versions) and Cinema 4d (all versions) as both do a very good job with boolean modeling. The plus side is that your TS or C4D created models will improve in quality while at the same time also requiring less memory.
Minus side of Bryce 6.x
It stinks at import and export. Texture animation is broken. Overlapping Volumetrics (including fuzzy transparencies) remains broken (worked in Bryce 4, broken in Bryce 5 and above). I find I often have to import in to bryce 5.5, export it as a OBP and load the OBP in to Bryce 6.1 so I can render it at full speed and with the fancy lighting. It is the same with exports. Obviously Bryce 5.5 can not export boolean objects. But Bryce 5.5 can export rocks, terrains, imported meshes... and does so more reliability than Brcey 6. Bryce 6.x has slightly worse memory management. You sometimes need to exit the program completelty and reload it to continue working. There is a memory leak which is just infuriating. It can cause you to create a scene which you can never save. The only work around is to save often and not just to the same name and from time to time exit Bryce completely. The memory leak is reduced if you close and re-open your file. But, it is better to either restart Bryce or Restart your PC.
plus side of Bryce 6.x
On speed, and lighting, layout, file and library management... I find Bryce 6.x to be better to much better. It is MUCH faster on a dual-core PC. Bryce 5.x can only use a single core of the newer processors. While Bryce 6.x can use all of them. For non-units, it also has much better lighting options. Even on a single core it is around 5-15% faster depending on what you are doing.
I still love bryce, and it is still my favorite 3d application. But, I am VERY pissed off about the quality of the current version and the lack of support for it from Daz.
(appropriately enough, I used several of the textures from de_aztec.wad for my mesoamerican structures)
