It’s fine I have fun trying to see how much I can pile on it before it groans and gives up. It is a lot more than I could do with Br 5 and my old system.
Save often, but that has always been the secret of getting the best out of Bryce, and incremental saves so you always have a save that is only a few tweaks back just in case you do manage to corrupt a working file.
I have found that even if I do succeed in crashing Bryce almost always I can re open the crashed file, which certainly was not the case with older version, a crash in them was almost always a fatal crash.
AS you are using 10.6 you will be fine, except for one annoying bug with jpg texture imports, and there are a couple of work rounds to that one as stated here http://www.daz3d.com/forums/viewthread/19947/