I also have a big soft spot in my heart for Bryce; it was my first 3D app. Like many others though, I have moved to Carrara because it suits my workflow. BTW, you don't need to import rocks into Carrara, Simply make a few sphere primitives, give them different sizes, stretch a few on different axis, or squash them and then give them a displacement shader, of which there are hundreds available. Then if you put them in a surface replicator you can have incredible amounts of rocks and boulders in your scene without using any imports.