There IS a difference between Developer Preview 6 and Public Beta 2. They have changed a lot of things, most noticeably those new icons which are visible for the drives, as well as the Spotlight location in the menubar. It does seem more stable and my Preview is not crashing anymore with PB2. This seems more stable, they are making tweaks, changes, and adding stuff...but is not polished and fully ready for primetime yet. There are still bugs. Apple needs to have a better system for working with List View folders with more than 300 documents. That is still not perfected. If you choose "View by Date Added" when you reach a certain number it does not correctly list them or add new files in the correct top-down order, and it does not attribute the time and date to additional files added, after a certain number, say 300 or 400. For instance, a ffolder with saved e-mails or legal client files could present problems when you have a large number of files in list view. Apple had not fixed this issue in Mavericks and it is still persistent in Yosemite. I cannot see why this bug/issue cannot be fixed, because it a basic usability thing that plagues the system. It's a flaw of the Finder, and it needs to addressed.
That is food for thought.