In my experience I'd say the exact opposite. In general any .0 or .1 release is going to have more bugs than any .5 or .8 release. With any major software release, OS or otherwise, if you are sensitive to bugs you should always wait until it hits .3 or even higher.
This comment shows up with every Apple release that has release notes listing some fixes. Apple probably has thousands of bugs in their database. An update can potentially fix dozens of bugs, so they're not going to list all of them, particularly over the course of multiple seeded betas. In virtually every case, point updates fix more than what is listed in the release notes.
But I doubt the build number indicates so In Snow Leopard, the build numbers of each maintenance updates go by hundreds. Lion onwards, the numbers are so tiny, probably 1/10 of SL...